TechPedia - User contributions [en]

Zen C

2026-02-03T08:18:17Z

LunaStev: Created page with "{{Software infobox | Name = Zen C | Developer = '''Zuhaitz''' | Released = January 26, 2026 | Latest release= '''0.4.0''' | Extensions = ''.zc'' | License = '''MIT''' | Website = https://www.zenc-lang.org/ }} <div style="clear:right;"></div> == Overview == Zen C is a programming language developed by Zuhaitz that provides modern syntax while ultimately compiling to human-readable GNU C/C11 code. == Key Features == * High-level f..."

{{Software infobox
| Name = Zen C
| Developer = '''Zuhaitz'''
| Released = January 26, 2026
| Latest release= '''0.4.0'''
| Extensions = ''.zc''
| License = '''MIT'''
| Website = https://www.zenc-lang.org/
}}

<div style="clear:right;"></div>

== Overview ==
Zen C is a programming language developed by Zuhaitz that provides modern syntax while ultimately compiling to human-readable GNU C/C11 code.

== Key Features ==
* High-level features: Supports type inference, pattern matching, generics, traits, and async/await.
* C compatibility: Maintains 100% C ABI compatibility and interoperates seamlessly with C, C++, CUDA, and Objective-C.
* Portability: Supports APE (Actually Portable Executable) builds, allowing a single binary to run on various operating systems such as Linux, macOS, and Windows.

Programming languages

2026-02-03T08:15:39Z

LunaStev: /* Z */

= Programming languages =
A '''programming language''' is a formal system designed to express computations,
instruct computers, and describe algorithms.
Each language has its own syntax, semantics, and execution model,
allowing humans to represent procedures that machines can perform.

== Overview ==
Programming languages are central to computer science.
They serve as a bridge between human thought and machine execution,
enabling the expression of algorithms, data manipulation, and interaction with hardware and software.

They are used in education, research, industry, and even art,
playing a fundamental role in the advancement of human knowledge and technology.

== List of programming languages ==
Below is a list of programming languages covered in TechPedia.
The list is ordered alphabetically (numbers → A–Z → others).
When creating a new language page, add it here.

=== 0–9 ===
* [[1C:Enterprise]]
* [[4th Dimension]]

=== A ===
* [[Ada]]
* [[ALGOL]]
* [[APL]]
* [[Assembly language]]

=== B ===
* [[B]]
* [[BASIC]]
* [[Brainfuck]]

=== C ===
* [[C]]
* [[C/AL]]
* [[C Shell]]
* [[C--]]
* [[C++]]
* [[C*]]
* [[C＃]]
* [[Caché ObjectScript]]
* [[Caml]]
* [[Carbon]]
* [[Cayenne]]
* [[Cecil]]
* [[CESIL]]
* [[Céu]]
* [[Ceylon]]
* [[CFEngine]]
* [[CFML]]
* [[Cg]]
* [[Ch]]
* [[Chapel]]
* [[Charm]]
* [[CHILL]]
* [[CHIP-8]]
* [[ChucK]]
* [[Cilk]]
* [[Claire]]
* [[Clean]]
* [[Clipper]]
* [[CLIPS]]
* [[CLIST]]
* [[Clojure]]
* [[CLU]]
* [[CMS-2]]
* [[COBOL]]
* [[CobolScript]]
* [[Cobra]]
* [[CoffeeScript]]
* [[ColdFusion]]
* [[COMAL]]
* [[COMIT]]
* [[Common Intermediate]]
* [[Common Lisp]]
* [[COMPASS]]
* [[Component Pascal]]
* [[COMTRAN]]
* [[Concurrent Pascal]]
* [[Constraint Handling Rules]]
* [[Control Language]]
* [[Coq]]
* [[CORAL]]
* [[CorVision]]
* [[COWSEL]]
* [[CPL]]
* [[Cryptol]]
* [[Crystal]]
* [[Csound]]
* [[Cuneiform]]
* [[Curl]]
* [[Curry]]
* [[Cybil]]
* [[Cyclone]]
* [[Cypher Query Language]]
* [[Cython]]

=== D ===
* [[D]]
* [[Dart]]

=== E ===
* [[Eiffel]]
* [[Elixir]]
* [[Erlang]]

=== F ===
* [[F＃]]
* [[Fortran]]

=== G ===
* [[Go]]
* [[Groovy]]

=== H ===
* [[Haskell]]
* [[HTML]] (markup language)

=== J ===
* [[Java]]
* [[JavaScript]]
* [[Julia]]

=== K ===
* [[Kotlin]]

=== L ===
* [[Lisp]]
* [[Lua]]

=== M ===
* [[MATLAB]]
* [[Modula-2]]

=== N ===
* [[Nim]]

=== O ===
* [[Objective-C]]
* [[OCaml]]

=== P ===
* [[Pascal]]
* [[Perl]]
* [[PHP]]
* [[Prolog]]
* [[Python]]

=== R ===
* [[R]]
* [[Ruby]]
* [[Rust]]

=== S ===
* [[Scala]]
* [[Scheme]]
* [[Smalltalk]]
* [[Swift]]

=== T ===
* [[Tcl]]
* [[TypeScript]]

=== V ===
* [[V]]
* [[Verilog]]
* [[VHDL]]
* [[Visual Basic]]

=== W ===
* [[Wave]]
* [[Whitespace]]

=== Z ===
* [[Zen C]]
* [[Zeta]]
* [[Zig]]

=== Others ===
* [[Malbolge]]
* [[INTERCAL]]
* [[Esoteric programming languages]]

== See also ==
* [[Computer science fundamentals]]
* [[Compilers & tools]]
* [[Operating systems]]

----

''This article both introduces programming languages and serves as the central hub for the language list on TechPedia.''

Wave

2025-12-03T02:54:55Z

LunaStev:

{{Software Infobox
| Name = Wave
| Logo = [[File:Wave_logo.png|120px]]
| Developer = LunaStev
| ReleaseDate = January 14, 2025
| LatestVersion = v0.1.5-pre-beta
| Extension = .wave
| License = MPL-2.0
| Website = https://wave-lang.dev/
}}

<div style="clear:right;"></div>

'''Wave''' is a general-purpose programming language developed by system software engineer '''LunaStev'''.
Wave simultaneously pursues the performance of a low-level language and the abstraction of a high-level language, and its philosophy is ''“Reimagining Low-Level Programming”'' (the redefinition of low-level programming). Inheriting the language design philosophies of Rust and C-family languages, it is designed to enable development across various domains (systems, networking, web, AI, etc.) using a single language through new syntax structures and an integrated ecosystem.

Wave is a compiled language, and while it is fundamentally based on the LLVM backend, the long-term plan is to build a completely independent ecosystem centered around its proprietary toolchain, '''Whale'''. <ref>https://www.wave-lang.dev/docs/ecosystem/whale</ref>
It also provides an integrated environment for the language itself, including the package manager '''Vex''', the serialization format '''WSON''', and a set of standard libraries.

== History ==
* '''May 2024''': Wave development commences
* '''December 2024''': Initial LLVM-based compiler prototype completed
* '''January 14, 2025''': Wave official release (Version 0.0.1-pre-alpha)
* '''August 1, 2025''': v0.1.4-pre-beta released

== Key Features ==
The Wave language has the following characteristics:

== Example Code ==
This is an example from the official Wave website.

<syntaxhighlight lang="kotlin">
fun main() {
var name: str = "Wave";
let year: i32 = 2024; // immutable

println("Language: {}, Year: {}", name, year);
}
</syntaxhighlight>

== Applications ==
Wave is being developed with the intention of being used in areas such as:
* Systems programming (OS, drivers, embedded software)
* Web backend development

== See Also ==
* [[Programming languages]]
* [[C]]
* [[Rust]]

== References ==
* [https://github.com/wavefnd/Wave/ Wave GitHub repository]
* [https://wave-lang.dev/ Official Wave website]

[[Category:Programming languages]]

Wave

2025-12-03T02:54:27Z

LunaStev:

{{Software Infobox
| Name = Wave
| Logo = [[File:Wave_logo.png|120px]]
| Developer = LunaStev
| ReleaseDate = January 14, 2025
| LatestVersion = v0.1.5-pre-beta
| Extension = .wave
| License = MPL-2.0
| Website = https://wave-lang.dev/
}}

<div style="clear:right;"></div>

'''Wave''' is a general-purpose programming language developed by system software engineer '''LunaStev'''.
Wave simultaneously pursues the performance of a low-level language and the abstraction of a high-level language, and its philosophy is ''“Reimagining Low-Level Programming”'' (the redefinition of low-level programming). Inheriting the language design philosophies of Rust and C-family languages, it is designed to enable development across various domains (systems, networking, web, AI, etc.) using a single language through new syntax structures and an integrated ecosystem.

Wave is a compiled language, and while it is fundamentally based on the LLVM backend, the long-term plan is to build a completely independent ecosystem centered around its proprietary toolchain, **Whale**. <ref>https://www.wave-lang.dev/docs/ecosystem/whale</ref>
It also provides an integrated environment for the language itself, including the package manager '''Vex''', the serialization format '''WSON''', and a set of standard libraries.

== History ==
* '''May 2024''': Wave development commences
* '''December 2024''': Initial LLVM-based compiler prototype completed
* '''January 14, 2025''': Wave official release (Version 0.0.1-pre-alpha)
* '''August 1, 2025''': v0.1.4-pre-beta released

== Key Features ==
The Wave language has the following characteristics:

== Example Code ==
This is an example from the official Wave website.

<syntaxhighlight lang="kotlin">
fun main() {
var name: str = "Wave";
let year: i32 = 2024; // immutable

println("Language: {}, Year: {}", name, year);
}
</syntaxhighlight>

== Applications ==
Wave is being developed with the intention of being used in areas such as:
* Systems programming (OS, drivers, embedded software)
* Web backend development

== See Also ==
* [[Programming languages]]
* [[C]]
* [[Rust]]

== References ==
* [https://github.com/wavefnd/Wave/ Wave GitHub repository]
* [https://wave-lang.dev/ Official Wave website]

[[Category:Programming languages]]

Main Page

2025-11-08T07:00:08Z

LunaStev:

= Welcome to TechPedia =
''An open encyclopedia dedicated to computer science and modern technology.''

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<b>Build knowledge, connect the world, and share technology.</b>
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== Read in Other Languages ==
* [https://ko.techpedia.wiki Korean Wiki →]

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== About TechPedia ==
'''TechPedia''' is a free and collaborative wiki focused on computer science and technology.
Its mission is to provide accurate, reliable, and up-to-date information that reflects the latest advancements in the field.

Topics covered include:

* Programming languages — from C and C++ to emerging ecosystems such as Rust and Wave
* Computer science fundamentals — algorithms, data structures, and computational complexity
* Systems — operating systems, compilers, and low-level development
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MediaWiki:Sidebar

2025-10-21T01:15:30Z

Operating systems

2025-10-21T01:01:27Z

LunaStev: /* 3. Modern OS Layer Model */

== Overview ==
'''Operating System''' (OS) is the '''core control software''' of a computer system,
responsible for efficiently managing hardware resources and providing a standardized environment for applications and users.
An operating system is not merely a “manager of programs,”
but a '''software infrastructure''' that forms the foundation of the modern computing ecosystem.

The essence of an operating system lies in the “'''control and abstraction of resources'''.”
Hardware resources such as the CPU, memory, storage devices, networks, and peripherals
are inherently complex and asynchronous physical systems,
but the operating system transforms them into a logically unified abstract layer
so that users and applications can interact with them in a consistent manner.
This abstraction serves as the foundational language of computing,
and all modern application software exists solely upon this language.

An operating system is broadly composed of two main pillars:
* '''Kernel''' — The core layer responsible for resource management and hardware control.
* '''System Software Layer''' — Operates on top of the kernel and includes file systems, network stacks, drivers, process managers, and user interfaces.

The development of operating systems is closely tied to the history of computer science.
Starting from batch systems for single tasks in the early 1950s,
to time-sharing systems in the 1960s,
portable OS architectures based on [[Unix]] and [[C (programming language)]] in the 1970s,
the popularization of personal computer (PC) operating systems such as [[MS-DOS]] and [[Windows]] in the 1980s–1990s,
and the open-source ecosystems of [[Linux]] and [[Android]] in the 2000s and beyond,
operating systems have continually evolved alongside rapid hardware advancements.

Today’s operating systems are no longer just “hardware managers” but also serve as
the backbone of '''security, virtualization, cloud computing, AI, and network infrastructure'''.
Operating systems transcend the limitations of physical devices,
providing abstract environments such as virtual machines and containers,
thus forming the foundation of modern data centers and cloud platforms.

The design philosophy of an operating system varies depending on its implementation:
* The [[Linux kernel]] and Unix-based systems adopt a '''monolithic kernel''' structure, where all core functions are integrated within the kernel.
* [[Windows NT]] and the Darwin layer of [[macOS]] use a '''hybrid kernel''' structure, combining the stability of microkernels with the performance of monolithic kernels.
* Systems like [[Minix]] and [[QNX]] employ a '''microkernel''' structure, retaining only minimal kernel functions and running the rest in user space to ensure high stability and isolation.

The core functionalities of an operating system can be summarized as follows:
* '''Process and thread management''' — Creation, scheduling, synchronization, and termination of execution units.
* '''Memory management''' — Virtual memory, page replacement, memory protection, and address space separation.
* '''File system management''' — Logical storage structure of data and access control.
* '''I/O system control''' — Device drivers, buffering, and interrupt handling.
* '''Network management''' — TCP/IP stack, socket communication, routing, and protocol control.
* '''Security and access control''' — User authentication, permission management, and sandboxing features.
* '''Virtualization and container support''' — Technologies such as hypervisors, namespaces, and cgroups.

The design of modern operating systems extends beyond software engineering
into philosophical and societal realms.
An operating system serves as a '''digital constitution''',
deciding “what to permit and what to control.”
Such decisions are not mere technical choices,
but directly influence user freedom, privacy, data sovereignty,
and the ethical boundaries of artificial intelligence.

Representative modern operating systems include:
* Desktop/server: [[Windows]], [[Linux]], [[macOS]], [[FreeBSD]]
* Mobile: [[Android]], [[iOS]]
* Embedded/real-time: [[FreeRTOS]], [[VxWorks]], [[QNX]]

Thus, the operating system is not a single program,
but an “invisible platform” that supports the entirety of digital civilization.

== Core Functions ==
The functions of an operating system go beyond simply “executing programs and managing resources”;
they have evolved into a '''core mechanism that defines and controls the operating rules of the entire computer system'''.
These functions are implemented around the Kernel,
and include various layers that mediate between User Space and System Space.
What follows are the main functions that the operating system carries out and their technical significance.

=== 1. Process and Thread Management (Process and Thread Management) ===
One of the most important roles of the operating system is to manage CPU resources so that multiple programs can share them efficiently.
A Process is an instance of a program in execution,
and the operating system creates (Create), schedules (Schedule), synchronizes (Synchronize) and terminates (Terminate) it.

* '''Scheduling''' — The mechanism that determines the order of CPU allocation among processes, divided into preemptive and non‑preemptive types. Modern operating systems use dynamic priority‑based algorithms such as CFS (Completely Fair Scheduler) or Windows’ MLFQ (Multilevel Feedback Queue).
* '''Thread''' — The execution unit within a process, enabling lightweight parallel execution and resource sharing. With the advent of multi‑core CPUs, threads have become the core unit of OS schedulers; Linux supports POSIX threads based on `pthread`, Windows supports Win32 threads.
* '''Synchronization''' — Techniques like semaphores, mutexes, spinlocks are used to prevent race conditions and deadlocks.

In modern systems, the process management layer has expanded beyond simple CPU control
to structures based on namespaces and cgroups (Control Group) for running isolated execution environments such as containers (Container) or virtual machines (VM).

=== 2. Memory Management (Memory Management) ===
Memory management aims for multiple processes to use a limited physical memory efficiently and safely.
The operating system separates physical addresses (Physical Address) and virtual addresses (Virtual Address),
so that each process acts as if it has an independent memory space.

* '''Virtual Memory''' — Using page tables and the MMU (Memory Management Unit), the OS provides each process with an independent address space. This achieves both protection and isolation.
* '''Paging and Swapping''' — When memory is insufficient, some pages are temporarily moved to disk so that more processes can run concurrently.
* '''Cache and Buffer Management''' — Control of multi‑level memory hierarchies including CPU cache, file buffer, page cache, to maximize I/O efficiency.

Modern OS memory managers support various architectures such as NUMA (Non‑Uniform Memory Access), hardware virtualization (VT‑x, AMD‑V), and memory compression and sharing technologies (KSM, Memory Ballooning).

=== 3. File System Management (File System Management) ===
The operating system abstracts data storage devices into logical structures,
allowing users and applications to access them through the concept of “files”.

* '''File Structuring''' — Through metadata structures such as directory, inode, FAT, B‑Tree, data is managed hierarchically.
* '''Journaling''' — To prevent file system damage, changes are logged and then reflected to actual files. Examples include NTFS (Windows), ext4 (Linux), APFS (macOS).
* '''Permission and Access Control''' — Via POSIX permissions, ACL (Access Control List), Security Context, user‑specific access is controlled.
* '''File Cache and Buffering''' — To reduce disk I/O bottlenecks, read/write data are cached in memory to improve efficiency.

The file system has now evolved into more than simple storage structure,
into extended layers including encrypted file systems (EFS), network file systems (NFS, SMB),
and even cloud storage APIs.

=== 4. I/O System and Device Management (I/O System and Device Management) ===
The I/O system is the physical boundary layer connecting hardware devices and the kernel.
The operating system abstracts I/O requests so that applications can access standard APIs without knowing device specifics.

* '''Device Driver (Device Driver)''' — Kernel modules that control specific hardware devices; each OS provides its own driver model (Windows Driver Model, Linux Device Model).
* '''Interrupt Handling''' — An asynchronous signal handling system that allows the CPU to immediately detect external events.
* '''Buffering and Spooling''' — Data is temporarily stored and processed sequentially to mitigate I/O bottlenecks.

In modern systems, the I/O layer has expanded beyond simple disks and printers
to manage a wide range of devices such as GPU, sensors, network interfaces, USB, PCIe.

=== 5. Network Management (Networking) ===
The operating system integrates a network protocol stack to support communication between local systems or over the Internet.

* '''TCP/IP Stack Implementation''' — Provides a standardized network communication layer based on the socket API.
* '''Routing and NAT Management''' — Network path control functions including packet forwarding, address translation, firewall policies.
* '''Security Protocol Integration''' — Support system‑level encrypted communication such as TLS, IPSec, SSH.
* '''Virtual Network (Virtual Network)''' — In container and virtual machine environments, manage bridges, tunnels, overlay networks.

Modern OS treat networking not as a simple data channel,
but as an infrastructure of service, security, and virtualization.

=== 6. Security and Access Control (Security and Access Control) ===
To maintain system consistency and reliability, the operating system must strictly control user permissions and data access.

* '''Authentication''' — Verification of user identity (passwords, tokens, biometric, etc.).
* '''Authorization''' — Granting access rights to specific resources.
* '''Auditing''' — Tracking actions via system logs and security event records.
* '''Sandboxing''' — Isolating the execution environment of applications to prevent malicious behavior from spreading across the system.
* '''SELinux''', '''AppArmor''', '''Windows Defender''' are examples of implementations of these security policies.

Security operates at the kernel level in integration with hardware,
and is combined with firmware‑based protection technologies such as TPM (Trusted Platform Module) and Secure Boot.

=== 7. Virtualization and Resource Abstraction (Virtualization and Resource Abstraction) ===
In modern cloud environments, the operating system uses virtualization layers so that multiple logical systems can operate independently on a single physical device.

* '''Hypervisor (Hypervisor)''' — Technologies such as KVM, Hyper‑V, Xen provide virtualization management functions at the OS level or hardware‑supported level.
* '''Container (Containerization)''' — Technologies like Docker use OS kernel namespaces and cgroup features to implement process‑level isolation.
* '''Resource Control''' — Dynamically allocate and limit CPU, memory, network, I/O bandwidth.

Virtualization is considered an “extended role” of the operating system,
and functions as a core component of modern data center and cloud infrastructure.

== Structure ==
The structure of an operating system is not defined in a single form.
Its design varies according to '''philosophy, hardware architecture, performance priorities, security policies''',
and each structure is an answer to the fundamental question of “'''how far to include within the Kernel'''”.

The internal structure of an operating system can be broadly divided into the following three levels.

=== 1. Layered Architecture ===
An operating system is generally composed of the following layers:

* '''Hardware Layer''' — CPU, memory, storage devices, I/O devices and other actual physical resources.
* '''Kernel Layer''' — The core part that performs resource management, system calls, process scheduling, memory protection, etc.
* '''System Services Layer''' — Includes file systems, network stacks, device drivers, security, virtualization functions, etc.
* '''User Space''' — The area where shells, graphical interfaces, libraries, applications, etc. are executed.

This hierarchical structure “abstracts the complexity of hardware step by step”
so that applications can access hardware through standardized interfaces.
Most modern operating systems such as [[Unix]], [[Windows]], [[Linux]] are designed based on this layer model.

=== 2. Major Types of Kernel Architectures ===
The kernel structure of an operating system has evolved in various forms according to the balance of performance, stability, and scalability.

==== (1) Monolithic Kernel ====
A structure in which all core functions (process management, memory, file system, device drivers, etc.)
are executed in a single large kernel space.
Because all modules inside the kernel communicate directly, performance is high and system call overhead is low.
However, a bug or crash can affect the entire kernel.

* Representative examples: [[Unix]], [[Linux Kernel]], [[MS‑DOS]], [[Xv6]], [[FreeBSD]]
* Advantages: fast execution speed, single address space, simplified system call path
* Disadvantages: stability and security issues, maintenance complexity

Modern Linux kernel is classified as a complete monolithic kernel,
but it has evolved into a “modular monolithic” form by introducing module concepts that support dynamic loading.

==== (2) Microkernel ====
A structure that leaves only the minimal functionality inside the kernel, and
moves the remaining functions (file system, network, device drivers, etc.)
into independent processes in user space.
The kernel is responsible only for basic process scheduling, memory management,
and IPC (Inter‑Process Communication).

* Representative examples: [[Mach]], [[Minix]], [[QNX]], [[L4]], [[HURD]]
* Advantages: high stability, error‑resilience due to module isolation, improved security
* Disadvantages: performance degradation due to IPC overhead, implementation complexity

Microkernels are often used as the basic model in modern distributed systems, real‑time systems, and security‑enhanced OS designs.

==== (3) Hybrid Kernel ====
A form that combines the strengths of monolithic and microkernel architectures,
keeping the message‑based communication of microkernels while integrating some core functions into kernel space to reduce performance loss.
As a result, it can be described as a “partially monolithic microkernel” structure.

* Representative examples: [[Windows NT Kernel]], [[macOS]]’s [[XNU Kernel]], [[ReactOS]], [[Haiku]]
* Advantages: compromise between microkernel stability and monolithic kernel performance
* Disadvantages: structural complexity, difficulty in maintaining design consistency

Windows NT kernel is a representative example of a hybrid architecture,
separating the Executive layer and the HAL (Hardware Abstraction Layer) in kernel mode,
achieving both stability and portability.

==== (4) Exokernel ====
An experimental structure proposed in the 1990s at MIT,
where the operating system model exposes hardware resources almost directly to applications.
In other words, the kernel only acts as a “security arbiter”,
and user‑space libraries implement actual resource management policies.

* Representative examples: [[ExOS]], [[Nemesis]], [[MIT Exokernel Project]]
* Characteristics: extreme minimalism, performance maximization, customizable resource policies
* Disadvantages: complex user‑space management, cooperation needed between applications

Exokernels have indirectly influenced the design philosophy of high‑performance servers, hypervisors, and cloud nodes.

==== (5) Modular Kernel ====
A structure in which the kernel is divided into multiple independent modules,
which can be dynamically loaded or unloaded when needed.
This method maintains the performance of a monolithic kernel while securing maintainability and scalability.

* Representative examples: [[Linux Kernel]] (Loadable Kernel Modules), [[Solaris]]’s DDI/DKI
* Advantages: flexible feature extension, ability to add drivers without rebuilding the kernel
* Disadvantages: complexity of module dependencies, possible impact on kernel stability

=== 3. Modern OS Layer Model ===
Modern operating systems have evolved beyond kernel architecture,
to multi‑layer structures including virtualization layers, user‑space services, and security isolation layers.

The common structure of a modern OS can be represented as follows:

<syntaxhighlight lang="text">
┌───────────────────────────────┐
│ User Space │
├───────────────────────────────┤
│ Applications / Shell / GUI │
│ System Libraries (e.g., libc) │
├───────────────────────────────┤
│ System Call Interface │
├───────────────────────────────┤
│ Kernel Space │
├───────────────────────────────┤
│ Process / Memory / I/O Management │
│ File System / Network Stack │
│ Device Drivers / Security Modules │
├───────────────────────────────┤
│ Hardware Abstraction Layer (HAL) │
├───────────────────────────────┤
│ Hardware │
└───────────────────────────────┘
</syntaxhighlight>

This model shows that an operating system acts not as a “single program”
but as a '''hierarchical ecosystem'''.
Each layer has a clear boundary,
and communicates via system calls and interrupts.

=== 4. Virtualized & Distributed Architectures ===
With the advent of cloud computing and container technologies,
the structure of operating systems has expanded beyond physical boundaries into virtualization layers.

* '''Hypervisor Architecture''' — Technologies such as [[KVM]], [[Xen]], [[Hyper‑V]], [[VMware ESXi]] function as a “kernel on top of kernel” directly installed on hardware to manage multiple guest OSs.
* '''Container Architecture''' — Technologies such as [[Docker]], [[LXC]], [[Kubernetes]] utilize OS kernel namespaces and cgroup features to provide virtualization at the user‑space level.
* '''Distributed Kernel (Distributed Kernel)''' — Models such as [[Barrelfish]], [[Amoeba]], [[Plan 9 from Bell Labs]] treat multiple nodes as a single OS.

Such modern architectures have extended the operating system from a control program of a single machine
to a '''distributed infrastructure layer controlling entire networks'''.

=== 5. Summary ===
{| class="wikitable"
! Structure Type !! Representative Example !! Core Philosophy !! Major Advantages !! Major Disadvantages
|-
| Monolithic Kernel || Linux, Unix || Integration and simplicity || High performance, direct access || Vulnerable stability
|-
| Microkernel || Minix, QNX, Mach || Minimization and isolation || High stability, modularity || IPC overhead
|-
| Hybrid Kernel || Windows NT, XNU || Compromise design || Performance + stability || Complex architecture
|-
| Exokernel || ExOS || Extreme minimization || Performance maximization || Complex management
|-
| Modular Kernel || Linux, Solaris || Flexible extension || Dynamic feature management || Dependency issues
|}

Ultimately, the structure of an operating system is a compromise between “hardware constraints” and “human needs”.
If monolithic kernels pursued simplicity,
microkernels and hybrid kernels were compromises for stability and flexibility.
And today’s operating systems have evolved into a '''multi‑layered, virtualized living entity''' that synthesizes all these philosophies.

== History of Development ==
The history of operating systems is also the history of computer science.
Advancements in hardware, changes in programming paradigms, and the evolution of human–machine interfaces
have determined the structure and philosophy of operating systems.
The development of operating systems has generally gone through the following major historical stages.

=== 1. Early Days (1940s–1950s): The Era of Batch Processing ===
The first electronic computers ([[ENIAC]], [[EDSAC]]) did not have operating systems.
All programs were written directly in machine code,
and hardware could handle only one task at a time.

Later, in the mid-1950s, the concept of the operating system began to emerge
with the appearance of the '''Batch Processing System'''.
This system, which grouped jobs into units and executed them all at once,
was the first “automated interface” between the user and the hardware.

=== 2. Time-Sharing and Multiprogramming (1960s–1970s) ===
As computers became more powerful,
'''Time-Sharing Systems''' that allowed multiple users to use the system simultaneously emerged.
The most innovative project of this period was [[Multics]] (Multiplexed Information and Computing Service).
Multics implemented for the first time concepts that form the foundation of modern operating systems,
such as security, hierarchical file systems, and virtual memory.

The result of simplifying and restructuring the complexity of Multics was [[Unix]].
Written in [[C (programming language)]], Unix dramatically improved portability and scalability,
and with its philosophy of “everything is a file” as a single interface,
set a new standard for operating system design.

The developments of this period marked a turning point in which
“the operating system shifted from hardware control to human-centered interfaces.”

=== 3. The Era of Personal Computers (1980s) ===
From the late 1970s, as microprocessors became widespread,
operating systems moved from large mainframes to personal computers (PCs).
[[CP/M]], [[MS-DOS]] represented this environment.

Operating systems of this period were command-line based,
single-user environments rather than graphical user interfaces (GUIs).
However, with the release of the [[Apple Macintosh]] in 1984, GUI-based OSs became popular,
and later the [[Windows]] 3.x series followed this trend,
forming a new concept of “operating system = user experience.”

=== 4. Expansion of Networking and Distributed Computing (1990s) ===
The 1990s, with the popularization of networking and the internet,
was the period when operating systems began to internalize '''connectivity'''.
The [[Windows NT]] kernel, based on a modular hybrid architecture, NTFS, and the Win32 API,
provided stability and security in enterprise environments.

Meanwhile, [[Linux]] developed around the open-source community,
inheriting and expanding the philosophy of [[Unix]].
This opened a new paradigm of “decentralization of operating systems.”
Unix-based systems like [[FreeBSD]] and [[Solaris]]
also laid the foundation for large-scale networks and server environments.

=== 5. The Era of Mobile, Virtualization, and Cloud (2000s onward) ===
In the early 2000s, with the explosive growth of mobile devices,
operating systems shifted from a PC-centered to a '''mobile-centered paradigm'''.
[[Android]] and [[iOS]] efficiently handled multitasking, power management, and security policies
even in hardware-constrained environments,
establishing the concept of the “operating system in your hand.”

At the same time, in server and data center environments,
virtualization technologies such as [[VMware]], [[KVM]], and [[Xen]] spread.
Operating systems were no longer tied to a single system,
evolving into “managers of virtualized resources.”
This trend soon led to container-based
operating system-level virtualization such as [[Docker]] and [[Kubernetes]].

=== 6. Modern Era (2010s onward): Dissolution of Boundaries ===
Modern operating systems are no longer limited to physical computers.
In large-scale cloud infrastructures such as [[AWS]], [[Azure]], and [[Google Cloud]],
operating systems manage hundreds of thousands of virtual machines and containers simultaneously.
Moreover, with the spread of the Internet of Things (IoT) and edge computing,
operating systems have evolved into distributed intelligent structures
that operate simultaneously across numerous heterogeneous devices such as sensors, vehicles, satellites, and wearable devices.

At this point, the operating system is no longer a single “program,”
but functions as a '''global-scale software ecosystem'''.

== Modern Role ==
In the 21st century, the operating system has evolved beyond the traditional definition of “software that controls hardware,”
to become an entity responsible for the '''governance''' of the entire computing infrastructure.
This expands its meaning on three levels: technological, social, and philosophical.

=== 1. Technological Role: From Hardware Abstraction to Cloud Orchestration ===
The operating system still functions as an abstraction layer for hardware resources,
but now extends its control beyond physical devices to '''virtual resources''' and
'''cloud-native environments'''.

* Container technologies ([[Docker]], [[LXC]]) implement process-level virtualization using kernel namespaces and cgroups.
* Hypervisors ([[KVM]], [[Hyper-V]], [[Xen]]) run multiple virtual operating systems on physical hardware.
* Cloud orchestration ([[Kubernetes]]) automatically manages these virtual resources on a global scale.

Thus, the operating system has expanded from being a single system administrator
to a “distributed operating system” controlling billions of nodes.

=== 2. Social Role: Trust, Security, and Data Sovereignty ===
The operating system is like the “constitution” of digital society.
Through user permissions, data access, encryption, and security policies,
it determines who can control what.
The security model of the [[Windows NT kernel]], the policy-based access control of [[SELinux]],
and the sandbox structure of [[iOS]] are all expressions of such digital governance.

The security architecture of operating systems now extends beyond protecting individual systems
to social domains such as national security, corporate ethics, and personal data protection.

=== 3. Philosophical Role: The Boundary Between Control and Freedom ===
At its core, the operating system decides “who has the right to control the system.”
Open-source models ([[Linux]], [[FreeBSD]]) prioritize freedom and transparency,
while closed models ([[Windows]], [[iOS]]) prioritize stability and integrated ecosystems.
The balance between the two is less a technical choice and more of a '''philosophical declaration'''.

In the end, the modern operating system is not merely a technical product,
but a '''comprehensive embodiment of how human civilization manages digital space'''.

== Types ==
Operating systems can be classified in many ways, depending on their purpose, hardware architecture, real-time requirements, distribution method, and more.
Below are representative types of operating systems organized by major categories.

=== 1. Desktop & Personal Operating Systems ===
Operating systems used by general users on personal computers with graphical user interfaces (GUI).
* [[Windows]] series — Windows 1.0, 3.1, 95, 98, XP, 7, 10, 11, etc.
* [[macOS]] — Apple’s desktop OS, formerly known as Mac OS X or OS X
* [[Linux]] distributions — Ubuntu, Fedora, Debian, Arch Linux, openSUSE, Pop!_OS, Zorin OS, etc.
* [[ChromeOS]] — Google’s lightweight Linux-based OS with a cloud-centric structure
* [[Haiku]] — An open-source OS that inherits the philosophy of BeOS
* [[ReactOS]] — An open-source OS aiming for Windows compatibility
* [[AmigaOS]] — A classic multitasking OS designed for Amiga computers
* [[MorphOS]] — A PowerPC-based Amiga-family OS
* [[AROS]] — An open-source project compatible with the Amiga API

=== 2. Server & Enterprise Operating Systems ===
Operating systems for systems providing large-scale computation, databases, and network services.
* [[Windows Server]] series — Server OS based on the NT kernel
* [[Red Hat Enterprise Linux]] (RHEL) — A commercial enterprise Linux distribution
* [[Ubuntu Server]] — An open-source server OS based on LTS versions
* [[CentOS Stream]], [[Rocky Linux]], [[AlmaLinux]] — Community distributions compatible with RHEL
* [[SUSE Linux Enterprise Server]] (SLES) — A commercial server OS widely used in Europe
* [[FreeBSD]] — A BSD-family OS known for its stability and network performance
* [[OpenBSD]] — A security-focused BSD OS
* [[NetBSD]] — A BSD-family OS focused on portability
* [[Solaris]] / [[OpenSolaris]] / [[Illumos]] — UNIX OS from the Sun Microsystems lineage
* [[AIX]] — IBM’s UNIX OS
* [[HP-UX]] — Hewlett-Packard’s UNIX-based server OS
* [[Tru64 UNIX]] — A 64-bit UNIX system from DEC
* [[IRIX]] — A UNIX OS for high-performance graphics workstations by SGI

=== 3. Mobile Operating Systems ===
Operating systems used in smartphones, tablets, wearables, and other mobile devices.
* [[Android]] — Linux kernel-based, developed by Google
* [[iOS]] — Apple’s mobile operating system
* [[iPadOS]] — A fork of iOS specifically for iPads
* [[HarmonyOS]] — A distributed OS developed by Huawei
* [[KaiOS]] — A lightweight Linux-based OS for feature phones
* [[Tizen]] — A Linux-based platform developed by Samsung and Intel
* [[Sailfish OS]] — A successor to Meego, developed by Jolla (Finland)
* [[Ubuntu Touch]] — A Linux-based mobile OS
* [[LineageOS]], [[Pixel Experience]], [[GrapheneOS]] — Android open-source derivatives
* [[webOS]] — A Linux-based OS used by Palm, HP, LG, etc.
* [[BlackBerry OS]] / [[BlackBerry 10]]
* [[Symbian OS]] — A representative feature phone OS of the early 2000s
* [[Windows Mobile]] / [[Windows Phone]] — Microsoft’s mobile OS
* [[Fire OS]] — Amazon’s Android-based OS
* [[Pocket PC 2000]] — Part of the Windows Mobile family of mobile OSes

=== 4. Real-Time Operating Systems (RTOS) ===
Operating systems used in systems where response delays can be fatal (aviation, medical, industrial control, etc.).
* [[FreeRTOS]] — An open-source RTOS for microcontrollers
* [[VxWorks]] — A commercial RTOS by Wind River Systems
* [[QNX]] — A commercial microkernel-based RTOS (used in automotive, medical, industrial fields)
* [[RTLinux]] — A real-time extension based on Linux
* [[Zephyr OS]] — An open-source RTOS for IoT (led by the Linux Foundation)
* [[ThreadX]] — A lightweight system integrated into Microsoft Azure RTOS
* [[Integrity]] — A high-reliability RTOS by Green Hills Software
* [[µC/OS-II]] / [[µC/OS-III]] — Embedded RTOS developed by Micrium
* [[NuttX]] — A POSIX-compatible open-source RTOS (used in NASA's Ingenuity helicopter)
* [[eCos]] — An open-source RTOS for embedded systems
* [[T-Kernel]] — An RTOS based on Japan’s TRON project
* [[ChibiOS]] — A small RTOS for microcontrollers like STM32

=== 5. Embedded & IoT Operating Systems ===
Operating systems for systems with limited resources, such as sensors, appliances, and industrial devices.
* [[Embedded Linux]] — Linux tailored with a lightweight kernel for embedded use
* [[Android Things]] — Google’s OS for IoT devices
* [[TinyOS]] — An ultra-light OS for sensor networks
* [[RIOT OS]] — An open-source OS for IoT devices
* [[Contiki]] — OS for low-power wireless networks
* [[Mbed OS]] — IoT OS based on Arm Cortex-M
* [[OpenWrt]] — A Linux distribution for network routers
* [[uClinux]] — A Linux variant for processors without MMU
* [[Fuchsia OS]] — Google’s next-generation microkernel-based OS
* [[AliOS Things]] — Alibaba’s IoT operating system

=== 6. Cloud & Virtualization Operating Systems ===
Operating systems that efficiently manage resources in virtual machines, containers, and data center environments.
* [[CoreOS]] — Linux-based OS optimized for running containers
* [[Flatcar Linux]] — Open-source successor to CoreOS
* [[RancherOS]] — Lightweight OS centered around Docker containers
* [[Photon OS]] — A virtualization-friendly OS developed by VMware
* [[Google Container-Optimized OS]] — Cloud OS for Google Cloud Platform
* [[Amazon Linux]] / [[Bottlerocket]] — AWS-specific cloud OSes
* [[Azure Sphere OS]] — A security-focused OS by Microsoft for IoT
* [[XenServer]] — Hypervisor-type server OS by Citrix
* [[Proxmox VE]] — Open-source virtualization platform based on KVM and LXC
* [[OpenNebula]] / [[CloudStack]] / [[OpenStack]]-based OS environments

=== 7. Educational & Experimental Operating Systems ===
Operating systems designed for learning OS structure, theory, and research purposes.
* [[Minix]] — Designed by Andrew S. Tanenbaum for educational use (Unix-based)
* [[Xv6]] — A modern Unix remake developed at MIT for education
* [[Nachos]] — Simulator for university OS courses
* [[Pintos]] — A learning OS framework based at Stanford
* [[OS161]] — An educational OS for hardware simulators
* [[ToaruOS]] — An experimental OS based on C and x86
* [[SerenityOS]] — A desktop-style experimental OS built by a solo developer

=== 8. Mainframe & HPC Operating Systems ===
High-performance and high-reliability OSes used in mainframes and supercomputers.
* [[z/OS]] — IBM’s operating system for mainframes
* [[z/VSE]], [[z/VM]] — IBM OSes for virtualization and partitioned environments
* [[Cray OS]] / [[UNICOS]] — UNIX-family OSes for supercomputers
* [[Compute Node Linux]] (CNL) — Linux for HPC nodes
* [[Blue Gene OS]] — Lightweight kernel for IBM’s supercomputer
* [[AIX]] — UNIX OS for IBM Power Systems
* [[CNK]] — Kernel OS for IBM Blue Gene

=== 9. Historical & Legacy Operating Systems ===
Classic systems that marked major turning points in computing history.
* [[Multics]] — Prototype for modern operating system concepts
* [[Unix]] — Established portability and the single-interface philosophy
* [[MS-DOS]] — Popularized the personal PC operating system
* [[CP/M]] — Early OS for microcomputers
* [[OS/2]] — Joint operating system by IBM and Microsoft
* [[BeOS]] — Advanced OS optimized for multimedia
* [[NeXTSTEP]] — Predecessor to macOS, GUI-based and object-oriented
* [[Plan 9 from Bell Labs]] — Experimental OS with distributed filesystem philosophy
* [[Inferno OS]] — Network-centric virtual machine OS
* [[RISC OS]] — Early desktop OS for ARM-based systems
* [[GEOS]] — Graphical OS for low-spec devices
* [[OS/360]] — A landmark system in the IBM mainframe era

=== 10. Special-Purpose Operating Systems ===
Operating systems specialized for specific industries, devices, or environments.
* [[AUTOSAR]] / [[OSEK]] — Standardized RTOS for automotive control
* [[VxWorks 653]] — Supports ARINC 653 for avionics systems
* [[Integrity-178B]] — Real-time OS for aviation certification
* [[LynxOS]] — High-reliability OS for military and aerospace use
* [[Cisco IOS]] / [[NX-OS]] — Operating systems for network routers and switches
* [[JunOS]] — OS for Juniper Networks devices
* [[Arista EOS]] — Cloud switching device OS
* [[PlayStation OS]], [[Xbox OS]], [[Nintendo Switch OS]] — Dedicated OSes for game consoles
* [[watchOS]], [[tvOS]], [[Wear OS]], [[Tizen Wearable]] — OSes for wearables and TVs
* [[Automotive Grade Linux]] — OS for vehicle infotainment systems
* [[SpaceOS]] / [[RTEMS]] — Operating systems for aerospace and NASA
* [[INTEGRITY]] — OS for US military and defense industries
* [[Symobi]] — Multicore real-time OS

=== 11. Hypervisor & Virtual Machine Operating Systems ===
Operating systems that directly manage virtualization or operate as hypervisors.
* [[VMware ESXi]]
* [[Microsoft Hyper-V Server]]
* [[Xen]] / [[XenServer]]
* [[KVM]] (Kernel-based Virtual Machine)
* [[QEMU]] (Simulation + virtualization environment)
* [[Oracle VirtualBox]]
* [[bhyve]] — A FreeBSD-based hypervisor

=== 12. Other Categories ===
* '''Portable OS''': [[KolibriOS]], [[MenuetOS]], [[TempleOS]] — Single floppy/USB executable OS
* '''Security-focused OS''': [[Tails]], [[Qubes OS]], [[Whonix]] — Anonymity and virtualization isolation focused
* '''Cluster OS''': [[MOSIX]], [[OpenSSI]] — Manage multiple nodes as a single system
* '''Distributed OS''': [[Amoeba]], [[Barrelfish]], [[Google Fuchsia]], [[Plan 9]]
* '''Experimental kernel OS''': [[Redox OS]], [[HelenOS]], [[Genode OS Framework]]
* '''Personal developer OS''': [[SerenityOS]], [[ToaruOS]], [[TempleOS]], [[Sortix]]
* '''Next-generation OS research projects''': [[Carbon OS]], [[SkyOS]], [[Vapor OS]] (in development)

== Related Articles ==
* [[Windows]]
* [[Windows NT]]
* [[Linux Kernel]]
* [[Unix]]
* [[macOS]]
* [[Android]]
* [[iOS]]

== References ==
* Andrew S. Tanenbaum, ''Modern Operating Systems'' (Prentice Hall)
* Silberschatz, Galvin, and Gagne, ''Operating System Concepts'' (Wiley)
* William Stallings, ''Operating Systems: Internals and Design Principles'' (Pearson)

Operating systems

2025-10-21T01:00:43Z

LunaStev: Created page with "== Overview == '''Operating System''' (OS) is the '''core control software''' of a computer system, responsible for efficiently managing hardware resources and providing a standardized environment for applications and users. An operating system is not merely a “manager of programs,” but a '''software infrastructure''' that forms the foundation of the modern computing ecosystem. The essence of an operating system lies in the “'''control and abstraction of res..."

Main Page

2025-10-19T01:29:53Z

LunaStev:

= Welcome to TechPedia =
''An open encyclopedia for computer science and modern technology.''

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== About TechPedia ==
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Our goal is to provide accurate, reliable, and up-to-date knowledge covering:

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== Explore by Topic ==
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C

2025-10-18T09:35:25Z

LunaStev:

{{Software infobox
| Name = C
| Logo = [[File:C_logo.png|120px]]
| Developer = Dennis Ritchie
| Released = 1972
| Latest release= C17 (2018)
| Extensions = .c, .h
| License = ISO/IEC 9899
| Website = https://www.open-std.org/jtc1/sc22/wg14/
}}

== Overview ==
'''C''' is a general-purpose programming language developed by '''Dennis Ritchie''' in the early 1970s at [[Bell Labs]].
At that time, Bell Labs — led by [[Ken Thompson]] and Ritchie — was developing a new operating system called [[Unix]],
and during this process, the limitations of assembly-based systems became apparent.

In the early 1970s, every computer had its own unique instruction set,
and porting an operating system or compiler required rewriting the entire codebase.
To solve this problem, Bell Labs set a goal to create a '''“portable operating system”''',
and to achieve this, they needed a new language that preserved the low-level control of assembly
while providing the structural expressiveness of a high-level language.

It was in this context that C was born.
Ritchie improved upon [[B]], originally developed by Thompson,
introducing a more efficient and machine-friendly design.
C was first completed in 1972, and by 1973, the entire Unix kernel was successfully rewritten in C.
This event marked a major turning point in computer science history,
establishing C as a “system-level language.”

The greatest innovation of C lies in its philosophy as a '''“machine-oriented high-level language.”'''
This concept balances performance and abstraction
by allowing direct hardware control while organizing code
into functions and logical blocks.

C was designed around the following technical principles and philosophies:
* '''Low-level accessibility''' — direct memory manipulation via pointers (<code>*</code>) and the address operator (<code>&</code>).
* '''High-level structuring''' — logical code organization using conditionals, loops, functions, and structures.
* '''Minimalism''' — exclusion of unnecessary syntax, providing flexibility through simplicity.
* '''Portability''' — independence from specific hardware, enabling recompilation on different architectures.

Furthermore, C allows explicit hardware control
while maintaining simplicity and readability suitable for human developers.
Thanks to this balance, C became a foundational language across nearly all domains —
including compilers, operating systems, embedded systems, databases, and game engines.

The structural simplicity of C influenced the design of countless later languages.
[[C++]], [[Objective-C]], [[C#]], [[Rust]], [[Go]], and [[Wave]]
inherit and extend C’s syntax, memory model, function structure, and control flow.
As a result, C is regarded not merely as a language but as
an '''architectural prototype of programming language design.'''

Even today, C continues to serve as the standard for new language and system design,
remaining indispensable in operating system development, microcontroller programming,
and modern runtime implementations.
Its philosophical essence can be summarized by the following statement:

''“C is not just a programming language; it is a way of thinking about machines.”'' — Dennis Ritchie

== History ==
The evolution of C is not merely a story of syntax changes,
but a process intertwined with the development of operating systems, compilers, and hardware architecture.
Since its birth in the early 1970s, C has undergone several rounds of standardization,
laying the foundation for modern programming language design.

=== 1970s: Birth and Establishment ===
C was developed in 1972 at [[Bell Labs]] by '''Dennis Ritchie'''.
It was influenced by [[B]] and [[BCPL]],
and designed to efficiently implement the [[Unix]] kernel on the PDP-11 computer system.

In 1973, when the Unix kernel was largely rewritten in C,
it became the first language to enable a “machine-independent operating system implementation.”
This milestone introduced the concept of portability to the software industry.

In 1978, Ritchie and [[Brian W. Kernighan]] published
''The C Programming Language'' (commonly known as '''K&R C''').
The book became a de facto standard,
and compiler developers worldwide used it as the basis for C implementations.

=== 1980s: The Beginning of Standardization (ANSI C) ===
As C was used across different environments,
syntax discrepancies between compilers grew significantly,
creating the need for standardization.

In 1983, the '''ANSI X3J11 Committee''' was formed
to establish an official standard specification,
and in 1989, the American National Standards Institute (ANSI) approved it.

This standard, known as '''ANSI X3.159-1989''', or simply '''ANSI C''' or '''C89''',
included the following major changes:
* Clear definition of function declaration format (prototype introduction)
* Addition of standard libraries <code>stdlib.h</code>, <code>string.h</code>, <code>assert.h</code>
* Improvements to enumerations (<code>enum</code>) and constant expressions
* Establishment of a standard I/O model (<code>stdio.h</code>)

ANSI C was later adopted as an international standard by ISO in 1990,
becoming '''ISO/IEC 9899:1990''', also known as '''C90'''.

=== 1990s: The Foundation of Modern Syntax (C99) ===
After the publication of the C89/C90 standard,
C needed to adapt to rapidly advancing hardware and compiler technologies.
This led to the release of a new standard, '''C99''', in 1999.

Key changes introduced in C99 include:
* Addition of <code>//</code> single-line comments (for C++ compatibility)
* Introduction of <code>inline</code> functions for performance optimization
* Support for Variable Length Arrays (VLA)
* New integer and complex types (<code>long long</code>, <code>_Complex</code>)
* Introduction of the <code>_Bool</code> type and <code>stdbool.h</code> header
* Provision of fixed-width integer types via <code>stdint.h</code> (e.g., <code>int32_t</code>)

During this era, C was widely used across embedded systems, network devices, and scientific computing,
establishing itself as an “industrial standard language.”

=== 2010s: Parallelism and Stability (C11, C17) ===
With the rise of multicore processors, C officially embraced parallel programming.
Released in 2011, '''C11''' became the first C standard to define a formal memory model and thread safety.

Core features of C11:
* Multithreading support (<code>_Thread_local</code>, <code>atomic</code> types)
* Static assertions (<code>_Static_assert</code>)
* Support for anonymous structs and unions
* Unicode expansion (<code>uchar.h</code>)
* Safer standard functions (<code>gets()</code> removed, <code>snprintf()</code> recommended)

C11 is widely regarded as the standard that defined “modern system-level C.”

In 2018, '''C17''' (ISO/IEC 9899:2018) was released,
not as a major feature update, but as a bug-fix and cleanup revision,
serving as a stable edition of C11.

=== 2020s: Modern Refinement (C23) ===
Published in 2023, '''C23''' preserves the 50-year-old philosophy of C
while incorporating select features from modern programming languages.

Major updates include:
* Introduction of the <code>nullptr</code> keyword (as a safer alternative to <code>NULL</code>)
* Standardization of UTF-8 string literals (<code>u8""</code>)
* Addition of the <code>typeof</code> operator and type inference expressions
* Support for <code>constexpr</code>-like constant evaluation
* Formal introduction of the <code>static_assert</code> syntax
* New <code>embed</code> directive for embedding binary data

C23 is regarded as “a practical evolution that modernizes C
without transforming it into an entirely new language,”
reflecting contemporary system and compiler design principles.

From its origins as the Unix development language in the 1970s
to its continued dominance in the 2020s,
C remains the '''standard language for operating systems, compilers, embedded systems, and hardware control'''.
Even after more than 50 years, its philosophy and structure have changed little,
and C continues to be “the simplest yet most fundamental programming language.”

== Philosophy ==
The design philosophy of C is not merely a collection of syntactic rules,
but rather a '''thought paradigm''' for understanding and manipulating computer hardware.
Dennis Ritchie defined C as a “machine-oriented high-level language,”
meaning that C is more than just a programming tool —
it represents a way of thinking about computers themselves.

The philosophy of C can be summarized in four core principles.

=== 1. Minimalism ===
C was designed under the principle of “providing only what is necessary.”
The language defines only a small set of core constructs,
leaving complex functionalities to be implemented directly by the programmer.
Automated abstractions such as garbage collection, classes, and exception handling
were deliberately excluded.

This philosophy grants programmers '''absolute freedom and responsibility''',
allowing powerful systems to be built from a small language core.
This design approach was later inherited by the [[Unix]] philosophy,
forming the basis of the principle “Do one thing and do it well.”

=== 2. Machine-Oriented Abstraction ===
C aims to be a high-level language capable of directly interacting with hardware.
This embodies the idea of '''“abstraction over machine code”''',
allowing programmers to control memory addresses, pointers, and register-level operations
without writing assembly code.

This concept goes beyond hardware-friendly syntax.
C encourages programmers to “understand the machine as it truly operates.”
Thus, C serves as a linguistic interface between hardware-level control
and higher-level logical structures.

=== 3. Portability and Implementation Freedom ===
C is a compiler-centered language —
that is, its implementation (the compiler) matters more than the language definition itself.
The language provides only minimal rules,
while compilers are responsible for adapting them to different platforms.

This structure realized the concept of “write once, run anywhere.”
One of C’s core ideas is that “a language should not be bound to a specific machine,”
which was the fundamental reason [[Unix]] could be ported across diverse hardware.

At the same time, C deliberately allows '''undefined behavior''',
maximizing compiler optimization and implementation freedom.
Although rare in modern languages,
this approach was key to preserving C’s performance and simplicity.

=== 4. Freedom and Responsibility ===
C gives nearly all control to the programmer.
Memory management, type casting, pointer arithmetic, and bit operations
are all left in the user’s hands.
Safety mechanisms are minimal,
and incorrect operations can immediately lead to crashes or undefined results.

This design reflects the philosophy of prioritizing “control over safety.”
C does not protect the programmer —
instead, it offers the same level of freedom as the machine itself.
This attitude solidified C’s identity as a “language equal to the machine.”

=== 5. Simplicity and Extensibility ===
C is simple, yet capable of expressing all forms of complexity.
Though the language is small, its composability allows developers to build
operating systems, compilers, graphics engines, and virtual machines.

This is why C is often described as “a small language, but a complete one.”
As Ritchie once said:
:''"C was not designed to hide the machine, but to express it efficiently."''

In other words, C’s simplicity is not a limitation of expression,
but a deliberate choice to maximize expressive efficiency.

=== 6. Philosophical Influence on Modern Languages ===
C’s philosophy became the foundational principle for many later languages:
* [[C++]] — added object-orientation and encapsulation atop C’s structure.
* [[Rust]] — inherited C’s performance and low-level control while reinforcing safety.
* [[Go]] — applied C’s simplicity and explicit control to modern system programming.
* [[Wave]] — reimagined and modernized C’s memory model and philosophy as a next-generation low-level language.

Thus, C has transcended its role as a language,
becoming the '''philosophical origin of programming languages'''.
Its core ideals — minimalism, portability, control, and simplicity —
remain the foundation of all modern system programming languages to this day.

== Key Features ==
C combines structural simplicity with low-level hardware control,
achieving both high performance and flexibility through the following technical features.

=== 1. Static Type System ===
In C, every variable’s data type must be explicitly declared at '''compile time'''.
This ensures predictable program behavior and allows the compiler
to determine memory size and operation methods in advance.

For example, operations between <code>int</code> and <code>float</code> are strictly distinguished at compile time,
executing without runtime overhead.
This '''statically analyzed design''' contrasts with modern dynamic languages,
enabling C to closely correspond to hardware operations.

C also supports both '''implicit casting''' and '''explicit casting''',
granting programmers full control over type conversions.
While powerful, these conversions may cause '''precision loss''' or '''overflow errors''' if misused.

=== 2. Pointers and Direct Memory Access ===
One of C’s most distinctive features is the concept of pointers.
A pointer holds a memory address as its value,
allowing direct reading and writing to memory regions.

<syntaxhighlight lang="c">
int a = 10;
int *p = &a;
printf("%d\n", *p); // prints 10
</syntaxhighlight>

Pointers are both the source of C’s power and its danger.
They enable indirect access to arrays, functions, and structures,
making them indispensable in low-level development such as kernels and drivers.

However, incorrect address access can cause a '''Segmentation Fault''',
which is why C is often described as an “unsafe but predictable” language.

=== 3. Manual Memory Management ===
C does not include garbage collection (GC).
Memory allocation and deallocation are entirely the programmer’s responsibility.

<syntaxhighlight lang="c">
int *arr = malloc(sizeof(int) * 5);
...
free(arr);
</syntaxhighlight>

Functions like <code>malloc()</code>, <code>calloc()</code>, <code>realloc()</code>, and <code>free()</code>
are defined in the standard library <code>stdlib.h</code>.
This manual management model offers '''maximum performance''',
but improper use can lead to '''memory leaks''' or '''double-free errors'''.

Unlike modern languages with automatic memory management,
C’s model reflects its philosophy of total system resource control.

=== 4. Preprocessor ===
Before actual compilation, the C compiler performs a '''preprocessing''' phase.
This processes directives beginning with the <code>#</code> symbol,
providing significant structural flexibility to the language.

Common preprocessor directives include:
* <code>#include</code> – include external header files
* <code>#define</code> – define macros
* <code>#ifdef</code>, <code>#ifndef</code>, <code>#endif</code> – conditional compilation

Although technically just text substitution,
the preprocessor provides flexibility for C’s build system
and is essential for managing platform-specific code in large projects.

=== 5. Structured Programming ===
C is a procedural language that adopts block structures to implement '''structured programming'''.
It organizes control flow into functions
and provides explicit structures using <code>if</code> statements, loops (<code>for</code>, <code>while</code>),
and the <code>switch</code> statement.

<syntaxhighlight lang="c">
for (int i = 0; i < 5; i++) {
printf("%d\n", i);
}
</syntaxhighlight>

This design improved readability and maintainability,
breaking away from the linear control flow of [[B language]] and [[assembly language]],
and establishing the concept of “logical program composition.”

Later languages such as [[Pascal]], [[C++]], and [[Rust]] inherited this paradigm.

=== 6. Function-Centric Architecture ===
C follows the rule that “all code executes within a function.”
Every executable program must have a <code>main()</code> function,
and all functions must declare explicit return types and parameter lists.

<syntaxhighlight lang="c">
int add(int a, int b) {
return a + b;
}
</syntaxhighlight>

Since C89, the function '''prototype''' format was introduced,
allowing compilers to check argument types and improve type safety at call time.

C’s function architecture influenced later developments such as
[[C++]] methods, [[Rust]]’s functional model, and [[Wave]]’s chain APIs.

=== 7. Platform Independence ===
C was designed with the principle of “not being tied to any machine.”
Instead of using assembly code specific to a CPU or OS,
it enables hardware-independent source code that compilers translate appropriately.

Portability is one of C’s defining features,
allowing the same code to be recompiled and run on Windows, Linux, macOS, Unix, and more.

This is made possible by features like <code>sizeof</code>, <code>typedef</code>,
and the <code>std*</code> family of types, which abstract differences in memory size across platforms.

=== 8. Standard Library ===
The C Standard Library is a core component that extends the language’s functionality.
It includes file I/O, string manipulation, mathematical operations, and memory management,
enabling basic system-level tasks without OS-specific calls.

Key header files include:
* <code>stdio.h</code> – standard input/output
* <code>stdlib.h</code> – memory management and utilities
* <code>string.h</code> – string operations
* <code>math.h</code> – mathematical functions
* <code>time.h</code> – time-related utilities

The standard library is defined by the ISO standard,
and all C implementations are required to support it.

=== 9. Combination of Efficiency and Simplicity ===
C merges near-hardware efficiency with a readable high-level syntax.
As a result, C programs are both fast and lightweight while remaining human-readable.

This balance is one of the main reasons C has endured for over half a century,
remaining the standard for operating systems, compilers, embedded systems,
and all environments where “performance is everything.”

=== 10. Undefined Behavior ===
C explicitly allows certain undefined behaviors,
leaving room for compiler optimization.

Examples include pointer access beyond memory bounds
or using uninitialized variables — both considered “undefined behavior.”
This flexibility grants compiler implementers freedom,
but introduces potential risks to program stability.

It is both the reason for C’s remarkable performance
and the reason it demands a high level of responsibility from its programmers.

== Basic Structure ==
C programs follow the structural principle that “all code executes within functions.”
The most important entry point is the <code>main()</code> function,
where the program’s execution begins and ends.

C has a modular architecture.
Each source file (<code>.c</code>) contains one or more functions,
and header files (<code>.h</code>) are used to share declarations and interfaces between modules.

Every C program consists of three main components:
# '''Preprocessing section''' – directives such as <code>#include</code> and <code>#define</code>.
# '''Function section''' – <code>main()</code> and user-defined functions.
# '''Data section''' – global variables, constants, and structure definitions.

The following is the simplest example of a C program structure:

<syntaxhighlight lang="c">
#include <stdio.h>

int main(void) {
printf("Hello, World!\n");
return 0;
}
</syntaxhighlight>

The <code>#include</code> directive instructs the preprocessor to include the standard library,
and the <code>main()</code> function serves as the program’s entry point.
The C compiler always looks for and begins execution from <code>main()</code>.
This structure was later inherited by [[C++]], [[Rust]], and [[Wave]].

The structural simplicity of C became a standard paradigm
for compiler design, operating system development, and embedded systems programming.

=== Data Types ===
C’s data types are directly linked to the hardware memory model.
Each data type explicitly defines its '''storage size''', '''signness''', and permissible operations,
which determine both performance and memory efficiency.

The basic data types are as follows:

{| class="wikitable"
! Category !! Type !! Typical Size !! Description
|-
| Integer || <code>char</code> || 1 byte || Character or 8-bit integer
|-
| Integer || <code>short</code> || 2 bytes || Small integer
|-
| Integer || <code>int</code> || 4 bytes || Standard integer type
|-
| Integer || <code>long</code> || 4–8 bytes || Large integer
|-
| Floating-point || <code>float</code> || 4 bytes || Single-precision float
|-
| Floating-point || <code>double</code> || 8 bytes || Double-precision float
|-
| Boolean || <code>_Bool</code> || 1 byte || Introduced in C99
|}

Starting with the C99 standard,
<code>stdint.h</code> introduced fixed-width integer types such as
<code>int8_t</code>, <code>int32_t</code>, and <code>uint64_t</code>,
ensuring consistency across platforms.

C also supports composite data types:
* <code>struct</code> – groups multiple variables into a single logical unit.
* <code>union</code> – allows different types to share the same memory space.
* <code>enum</code> – defines a set of named constants.
* <code>typedef</code> – assigns aliases to existing types.

Although simple, C’s type system enables highly efficient code generation
that maps closely to hardware architecture.

=== Control Statements ===
C’s control statements define the logical flow of program execution.
Conditionals and loops are high-level abstractions of assembly-level branch instructions,
forming the foundation of all imperative programming logic.

* Conditionals: <code>if</code>, <code>else if</code>, <code>else</code>
* Selection: <code>switch</code> / <code>case</code>
* Loops: <code>for</code>, <code>while</code>, <code>do-while</code>
* Flow control: <code>break</code>, <code>continue</code>, <code>goto</code>

Example:

<syntaxhighlight lang="c">
for (int i = 0; i < 5; i++) {
if (i == 3) continue;
printf("%d\n", i);
}
</syntaxhighlight>

C’s control statements not only branch logic flow,
but also define the conceptual structure of imperative programming.
Because these statements map directly to machine instructions,
they enable compilers to perform efficient low-level optimizations.

=== Memory and Pointers ===
At the heart of C lies the ability to “manipulate memory addresses.”
This capability is what makes C not just a high-level language,
but a true '''system language'''.

A pointer is a variable that stores a memory address,
allowing indirect access or modification of another variable’s value.

<syntaxhighlight lang="c">
int x = 42;
int *ptr = &x;
printf("%d\n", *ptr);
</syntaxhighlight>

Here, <code>&</code> is the address-of operator,
and <code>*</code> is the dereference operator.
Thus, <code>*ptr</code> reads the actual memory value of <code>x</code>.

Through pointer operations, C allows low-level control such as:
* Direct memory access and modification
* Efficient array and string handling
* Function pointers for callback implementations
* Dynamic memory allocation (<code>malloc()</code>, <code>free()</code>)

This structure made C the optimal language for developing
operating systems, drivers, and firmware — domains that require direct hardware control.
However, incorrect memory access can cause immediate program crashes,
a risk considered part of C’s core philosophy:
“with freedom comes responsibility.”

=== Compilation Process ===
C is a '''compiled language''', meaning source code must be translated
into machine code before execution.
The compilation process consists of four main stages:

# '''Preprocessing''' — Handles directives such as <code>#include</code> and <code>#define</code>, performing conditional compilation and macro expansion.

# '''Compilation''' — Translates preprocessed code into assembly code, performing syntax analysis, type checking, and optimization.

# '''Assembly''' — Converts assembly code into object files (<code>.o</code>).

# '''Linking''' — Combines multiple object files and libraries into the final executable (<code>.exe</code> or ELF binary).
Example of a typical build process on Linux:

<syntaxhighlight lang="bash">
gcc -E main.c -o main.i # Preprocessing
gcc -S main.i -o main.s # Compilation
gcc -c main.s -o main.o # Assembly
gcc main.o -o main # Linking
</syntaxhighlight>

This multi-stage structure not only reflects C’s simplicity
but also served as the foundation model for [[compiler]] design.
Most modern compilers are built upon this architecture.

Throughout the entire process, C maintains its essence
as a language that expresses programs directly at the hardware level.
As a result, C enables efficient use of system resources
while allowing developers to write readable and structured code —
earning its reputation as a “machine-friendly high-level language.”

== Standard Macros ==
The C standard defines a set of '''predefined macros''' that every implementation (compiler) must provide.
These macros convey information about the compiler environment, standard version, and platform,
helping programs behave correctly across different systems.

Standard macros are recognized during the '''preprocessing stage''',
and are determined at '''compile time''', not at runtime.
In essence, the preprocessor in C functions as a “compiler–language interface” for environment metadata.

=== Major Macro List ===
The following table summarizes the representative macros defined by the ISO/IEC C standard and their purposes.

{| class="wikitable"
! Macro Name !! Description !! Introduced In
|-
| <code>__STDC__</code> ||
Indicates that the compiler conforms to the ANSI/ISO C standard.
A value of 1 signifies a standard-compliant implementation. || C89
|-
| <code>__STDC_VERSION__</code> ||
Specifies the supported version of the C standard.
Examples:
<code>199409L</code> → C94
<code>199901L</code> → C99
<code>201112L</code> → C11
<code>201710L</code> → C17
<code>202311L</code> → C23 || C90 and later
|-
| <code>__STDC_HOSTED__</code> ||
Indicates whether the environment is hosted (with standard library support)
or freestanding (independent, e.g., kernel or embedded).
1 = hosted, 0 = freestanding. || C99
|-
| <code>__FILE__</code> ||
String literal of the current source filename being compiled. || C89
|-
| <code>__LINE__</code> ||
Current line number in the source file. Useful for debugging and logging. || C89
|-
| <code>__DATE__</code> ||
Compilation date as a string (e.g., "Oct 17 2025"). || C89
|-
| <code>__TIME__</code> ||
Compilation time as a string (e.g., "14:30:42"). || C89
|-
| <code>__func__</code> ||
Returns the current function name as a string.
<syntaxhighlight lang="c">
void test() {
printf("%s\n", __func__);
}
</syntaxhighlight>
The above code prints "test". || C99
|-
| <code>__STDC_NO_ATOMICS__</code> ||
Defined as 1 if the compiler does not support <code>_Atomic</code>. || C11
|-
| <code>__STDC_NO_THREADS__</code> ||
Defined if the compiler does not support the standard threads library (<code>threads.h</code>). || C11
|-
| <code>__STDC_UTF_16__</code>, <code>__STDC_UTF_32__</code> ||
Indicates support for UTF-16 and UTF-32 character types. || C11
|-
| <code>__STDC_ANALYZABLE__</code> ||
Indicates whether static analysis features are supported. || C23
|-
| <code>__STDC_VERSION_STDINT_H__</code> ||
Specifies the version of <code>stdint.h</code>,
confirming support for standard integer types. || C23
|}

In addition to these, many compilers (e.g., GCC, Clang, MSVC)
provide their own proprietary extension macros.
For example, GCC defines <code>__GNUC__</code>, and MSVC defines <code>_MSC_VER</code>.

=== Role and Significance of Macros ===
Standard macros are not mere constants —
they serve as a '''linguistic interface between the compiler and the program'''.
By providing “compile-time environment information” rather than runtime data,
they allow conditional compilation and environment-specific behavior.

For instance, the following code performs compiler-specific conditional builds:

<syntaxhighlight lang="c">
#ifdef __GNUC__
printf("Compiled with GCC\n");
#elif defined(_MSC_VER)
printf("Compiled with MSVC\n");
#else
printf("Unknown compiler\n");
#endif
</syntaxhighlight>

This mechanism is one of the key reasons C achieves portability and implementation independence.
The source code remains identical,
but compilers can generate machine code tailored to their environments
by '''exposing system information through preprocessor macros'''.

=== Philosophical Aspect ===
C’s standard macro system is not merely an extension of preprocessing capabilities —
it embodies the language’s core philosophy:
'''“The language should be small, and the implementation should be powerful.”'''
The language defines only minimal promises,
delegating environmental awareness to the compiler through the preprocessor.

This design directly influenced the build systems and compiler metadata handling
in later languages such as [[C++]], [[Rust]], and [[Wave]].
In particular, the <code>build.meta</code> system in the Wave language
is considered an evolved form of C’s preprocessor macro concept.

Ultimately, standard macros serve as an intermediary layer
linking the language, compiler, and hardware —
the very mechanism that has allowed C to maintain its '''portability and implementation freedom'''
for over half a century.

== Influence on Other Languages ==
C became the foundation of nearly all major programming languages developed since the late 20th century.
Its influence extends far beyond syntax—encompassing philosophy, memory models, compiler design, and error-handling paradigms.
In other words, C did not merely shape “the form of languages” but “the way languages think.”

=== 1. Direct Descendant Languages ===
Languages that directly inherited C’s structure and syntax are collectively called the “C family.”
They evolved from C’s syntax, expression structure, and the concepts of pointers or references.

* '''C++''' — developed by [[Bjarne Stroustrup]] in 1983. It extended C by adding classes, objects, inheritance, templates, and other '''object-oriented''' features. Maintaining backward compatibility with C, C++ achieved both hardware-level control and high-level abstraction— earning the title “the language that expanded C’s philosophy.”

* '''Objective-C''' — created in the 1980s by [[Brad Cox]] and [[Tom Love]]. It combined C syntax with Smalltalk’s message-passing paradigm. It became the foundation for [[NeXTSTEP]], [[macOS]], and [[iOS]], defining Apple’s entire software ecosystem.

* '''C#''' — designed by [[Anders Hejlsberg]] at [[Microsoft]]. Built on C/C++ syntax, it was made to operate within the .NET Framework. It preserved C’s syntactic familiarity while introducing garbage collection and runtime safety.

* '''Java''' — simplified C++’s syntax and abstracted its memory model. Although it runs entirely within a virtual machine, its control structures, operators, and type system remain largely C-like.
All of these languages share the common goal of being “C-like but safer than C.”

=== 2. Indirect Influence (Structure and Philosophy) ===
C’s influence extends into language design philosophies as well.

* '''Rust''' — inherited C’s low-level control philosophy, but introduced ownership and compile-time validation to ensure memory safety. It is often described as “C without undefined behavior.”

* '''Go''' — retained C’s simplicity and explicit control structures while modernizing the model for concurrency and network programming. Since [[Ken Thompson]] and [[Rob Pike]]—key C developers—were involved, Go is regarded as a spiritual successor to C.

* '''D language''' — maintained the performance of C and C++ while integrating modern abstractions and managed memory. Strong interoperability with C code is one of its core traits.

* '''Swift''' — Apple’s successor to Objective-C, replacing the C-based runtime with a modern type system. Yet, its ABI and runtime architecture remain deeply influenced by C.

* '''Wave''' — a next-generation system language that fundamentally inherits C’s memory model and compiler philosophy, removing unnecessary complexity while experimenting with new syntax structures. It preserves C’s core concept of “machine-oriented abstraction.”
=== 3. Conceptual Influence Inside Languages ===
C’s legacy also extends deep into the internal structure of modern languages.

* '''Operator Semantics''' — Most languages directly reuse C’s operator system. Examples include <code>++</code>, <code>--</code>, <code>==</code>, <code>!=</code>, and <code>+=</code>. This syntax has effectively become the “industry standard operator notation.”

* '''Standard Library Architecture''' — The structure of C’s headers—<code>stdio</code>, <code>stdlib</code>, and <code>string</code>— laid the groundwork for modern module and package systems.

* '''Compilation Model''' — The pipeline of preprocessing → compilation → assembly → linking was inherited by [[C++]], [[Objective-C]], [[Rust]], and [[Wave]].

* '''Undefined Behavior Concept''' — A philosophical legacy of C. Some languages have eliminated it entirely (Rust, Swift), while others retain it in restricted form (C++, D).
=== 4. Influence on Programming Culture ===
C’s impact is not limited to technology—it shaped programming culture itself.

* The “Hello, World!” program tradition originated from the textbook ''The C Programming Language''.

* The concept that “a function is the fundamental unit of a program” became a universal assumption in language design after C.

* C’s syntax became the shared grammar of education, research, and industry. Today, most programmers can learn new languages quickly because they share C-style syntax.
=== 5. Philosophical Legacy ===
C is not merely a starting point for functionality—
it became the '''philosophical benchmark''' for language design.

Its influence continues along three fundamental axes:
* '''The Power of Simplicity''' — remove unnecessary abstractions and focus on essentials.
* '''Freedom of Control''' — programmers, not the language, govern memory.
* '''The Philosophy of Efficiency''' — extract performance directly from hardware.

This enduring spirit explains why all modern languages, no matter how advanced,
are still compared and analyzed against C.

Ultimately, C is more than a programming language—
it is the '''coordinate system of programming language history'''.
All languages can be classified as either “before C” or “after C.”

== Modern Evaluation ==
Although C was designed in the early 1970s,
it remains one of the most important system programming languages in the world even in the 2020s.
Its relevance is not merely as a “historical legacy,”
but because the very foundation of modern computing still rests upon it.

=== 1. Continuing Industrial Influence ===
Most operating systems, embedded firmware, compilers, network stacks,
and database engines are either written in C or deeply interconnected with it.
Notable examples include the [[Linux]] kernel, [[Windows]] NT kernel,
the Darwin layer of [[macOS]], [[PostgreSQL]], [[MySQL]], [[Redis]], and [[Nginx]].

These systems are not ordinary applications—
they form the '''core infrastructure of modern computing''' upon which all other software depends.
Thus, C serves as the “foundational language upon which all higher-level languages operate.”

Today, most hardware APIs and OS interfaces use
the C ABI (Application Binary Interface) as a standard.
This makes C not just a language but a '''common language of systems'''.

=== 2. Technical Strengths and Reasons for Survival ===
C has endured for over half a century due to several technical advantages:

* '''Deterministic Performance''' – With no garbage collection or runtime management, C provides fully predictable execution time and memory usage— essential for real-time systems, embedded devices, and kernel programming.

* '''Direct Hardware Control''' – Through pointers and bit-level operations, C allows direct access to memory, registers, and hardware devices— a capability no modern high-level language can fully replace.

* '''Simple Compilation Model''' – The consistent pipeline of preprocessing → compilation → assembly → linking avoids complex runtimes or virtual machines, resulting in higher portability and reliability.

* '''Transparency''' – C code maps closely to actual machine instructions, allowing programmers to predict memory layout and execution flow at the assembly level.
In short, C continues to dominate in three domains:
'''performance, simplicity, and control.'''

=== 3. Limitations and Criticisms ===
Despite its power, C has inherent limitations when faced with modern requirements.

* '''Lack of Memory Safety''' — While pointer arithmetic and manual memory management offer flexibility, they also introduce critical vulnerabilities such as buffer overflows, invalid references (segfaults), and use-after-free errors. Many security issues in the 2020s still originate from C code.

* '''Undefined Behavior''' — The C standard intentionally leaves certain behaviors undefined to enable optimization, but this leads to inconsistent results and compiler-dependent behavior.

* '''Limited Expressiveness''' — C lacks modern abstractions such as object orientation, generics, and exception handling. Writing large-scale systems often requires auxiliary languages or frameworks.

* '''Low Developer Productivity''' — Manual memory management, pointer handling, and difficult debugging make C less suitable for large-scale application development, where speed of development and maintainability are key.
For these reasons, C is no longer a “universal language.”
Successor system languages such as [[Rust]], [[Go]], and [[Wave]]
have emerged to pursue both safety and efficiency simultaneously.

=== 4. Educational and Philosophical Value ===
Nevertheless, C remains the '''core language of computer science education'''.
This is not simply due to tradition—
C most directly reveals “how computers truly work.”

Learning C means learning memory structure, pointers, compiler mechanics,
and CPU instruction models.
Thus, universities, research institutes, and corporate training programs worldwide
continue to teach C as “the language upon which all others are built.”

From a philosophical standpoint,
C embodies the principle that “humans should master the machine, not be protected from it.”
Even as modern languages pursue automation and abstraction,
this philosophy explains why C endures.

=== 5. C’s Current Role ===
Today, C is no longer a language of rapid innovation.
Instead, it is valued for its “unchanging stability” and “established ecosystem.”
C does not aim to reinvent itself like modern languages;
most updates focus on refinement and standardization.

Since the [[C23]] standard, C continues to thrive alongside
advanced compiler infrastructures such as [[LLVM]], [[GCC]], and [[Clang]],
remaining the dominant language for kernels, networking, hardware control, and real-time systems. Its role has shifted from “competitor among new languages”
to the enduring '''reference language for all others.'''

=== 6. Overall Evaluation ===
C remains both the foundation of modern software
and the philosophical axis of programming languages.
Its simplicity and risk are its greatest strengths,
and in terms of performance and control, it remains nearly unrivaled.

Ultimately, C is “an imperfect but fully comprehensible language,”
one that continues to define the very history of technology itself.

:''"C is both the origin and the gravity of programming languages."'' — TechPedia Editorial

== Implementation ==

=== The First C Compiler ===
The first C compiler had no official name and was developed by '''Dennis Ritchie'''. It was created around '''1972''', during the early days of the Unix system on the [[PDP-11]] platform. At that time, the compiler was implemented in [[Assembly language]] and functioned as a '''simple one-pass compiler''' that translated high-level code directly into machine code.

This early version was evolved from the [[B]] compiler, and as the C language itself stabilized, '''Dennis Ritchie rewrote the compiler in C''', achieving a '''fully [[Self hosting|self-hosting]]'''self-hosting '''environment'''. This process is considered a '''milestone in modern programming language development''', marking the '''first instance of a language capable of compiling itself'''. As a result, this compiler enabled the [[Unix]] '''kernel''' and its core utilities to be rewritten in C, laying the '''foundation for most modern system programming languages'''.

The source code he wrote in C is known as [https://github.com/LunaStev/legacy-cc legacy-cc]

=== Compiler ===

* [[GNU Compiler Collection]]
* [[LLVM|Clang / LLVM]]
* [[Microsoft Visual C++]]
* [[TinyCC]]
* [[Portable C Compiler]]
* [[Local C Compiler]]
* [[Small Device C Compiler]]
* [[Intel C Compiler]]
* [[Watcom C Compiler]]
* [[Borland Turbo C / C++]]
* [[Comeau C/C++]]
* [[LCC-Win32]]
* [[cproc]]
* [[8cc]]
* [[chibicc]]
* [[pcc68k]]
* [[vbcc]]
* [[cfront]]

=== Interpreter ===

* [[CINT]]
* [[Ch Interpreter]]
* [[Cling]]
* [[C-REPL]]
* [[CSharpRepl]]

== Related Articles ==
* [[Programming language]]
* [[B]]
* [[C++]]
* [[Rust]]
* [[Wave]]
* [[Assembly language]]
* [[Compiler]]
* [[Operating system]]
* [[Unix]]

== References ==
* Dennis M. Ritchie & Brian W. Kernighan, ''The C Programming Language'', Prentice Hall, 1978.
* ISO/IEC 9899:2023 – Information technology — Programming languages — C (C23 Standard).
* ISO/IEC JTC1/SC22/WG14, [https://www.open-std.org/jtc1/sc22/wg14/ Official C Language Standard Committee Website].
* Bell Labs Computer Science Research Center, ''The Development of the C Language'', Dennis Ritchie, 1993.
* Bjarne Stroustrup, ''A History of C++: 1979–1991'', ACM SIGPLAN Notices, Vol. 28, No. 3, 1993.
* GNU Project, [https://gcc.gnu.org GCC (GNU Compiler Collection) Documentation].
* Clang Project, [https://clang.llvm.org Clang: C Language Family Frontend for LLVM].

[[Category:Programming languages]]
[[Category:C family]]
[[Category:System programming]]
[[Category:1970s software]]

C

2025-10-18T09:31:24Z

LunaStev: /* Modern Evaluation */

{{Software infobox
| Name = C
| Logo = [[File:C_logo.png|120px]]
| Developer = Dennis Ritchie
| Released = 1972
| Latest release= C17 (2018)
| Extensions = .c, .h
| License = ISO/IEC 9899
| Website = https://www.open-std.org/jtc1/sc22/wg14/
}}

== Overview ==
'''C''' is a general-purpose programming language developed by '''Dennis Ritchie''' in the early 1970s at [[Bell Labs]].
At that time, Bell Labs — led by [[Ken Thompson]] and Ritchie — was developing a new operating system called [[Unix]],
and during this process, the limitations of assembly-based systems became apparent.

In the early 1970s, every computer had its own unique instruction set,
and porting an operating system or compiler required rewriting the entire codebase.
To solve this problem, Bell Labs set a goal to create a '''“portable operating system”''',
and to achieve this, they needed a new language that preserved the low-level control of assembly
while providing the structural expressiveness of a high-level language.

It was in this context that C was born.
Ritchie improved upon [[B]], originally developed by Thompson,
introducing a more efficient and machine-friendly design.
C was first completed in 1972, and by 1973, the entire Unix kernel was successfully rewritten in C.
This event marked a major turning point in computer science history,
establishing C as a “system-level language.”

The greatest innovation of C lies in its philosophy as a '''“machine-oriented high-level language.”'''
This concept balances performance and abstraction
by allowing direct hardware control while organizing code
into functions and logical blocks.

C was designed around the following technical principles and philosophies:
* '''Low-level accessibility''' — direct memory manipulation via pointers (<code>*</code>) and the address operator (<code>&</code>).
* '''High-level structuring''' — logical code organization using conditionals, loops, functions, and structures.
* '''Minimalism''' — exclusion of unnecessary syntax, providing flexibility through simplicity.
* '''Portability''' — independence from specific hardware, enabling recompilation on different architectures.

Furthermore, C allows explicit hardware control
while maintaining simplicity and readability suitable for human developers.
Thanks to this balance, C became a foundational language across nearly all domains —
including compilers, operating systems, embedded systems, databases, and game engines.

The structural simplicity of C influenced the design of countless later languages.
[[C++]], [[Objective-C]], [[C#]], [[Rust]], [[Go]], and [[Wave]]
inherit and extend C’s syntax, memory model, function structure, and control flow.
As a result, C is regarded not merely as a language but as
an '''architectural prototype of programming language design.'''

Even today, C continues to serve as the standard for new language and system design,
remaining indispensable in operating system development, microcontroller programming,
and modern runtime implementations.
Its philosophical essence can be summarized by the following statement:

''“C is not just a programming language; it is a way of thinking about machines.”'' — Dennis Ritchie

== History ==
The evolution of C is not merely a story of syntax changes,
but a process intertwined with the development of operating systems, compilers, and hardware architecture.
Since its birth in the early 1970s, C has undergone several rounds of standardization,
laying the foundation for modern programming language design.

=== 1970s: Birth and Establishment ===
C was developed in 1972 at [[Bell Labs]] by '''Dennis Ritchie'''.
It was influenced by [[B]] and [[BCPL]],
and designed to efficiently implement the [[Unix]] kernel on the PDP-11 computer system.

In 1973, when the Unix kernel was largely rewritten in C,
it became the first language to enable a “machine-independent operating system implementation.”
This milestone introduced the concept of portability to the software industry.

In 1978, Ritchie and [[Brian W. Kernighan]] published
''The C Programming Language'' (commonly known as '''K&R C''').
The book became a de facto standard,
and compiler developers worldwide used it as the basis for C implementations.

=== 1980s: The Beginning of Standardization (ANSI C) ===
As C was used across different environments,
syntax discrepancies between compilers grew significantly,
creating the need for standardization.

In 1983, the '''ANSI X3J11 Committee''' was formed
to establish an official standard specification,
and in 1989, the American National Standards Institute (ANSI) approved it.

This standard, known as '''ANSI X3.159-1989''', or simply '''ANSI C''' or '''C89''',
included the following major changes:
* Clear definition of function declaration format (prototype introduction)
* Addition of standard libraries <code>stdlib.h</code>, <code>string.h</code>, <code>assert.h</code>
* Improvements to enumerations (<code>enum</code>) and constant expressions
* Establishment of a standard I/O model (<code>stdio.h</code>)

ANSI C was later adopted as an international standard by ISO in 1990,
becoming '''ISO/IEC 9899:1990''', also known as '''C90'''.

=== 1990s: The Foundation of Modern Syntax (C99) ===
After the publication of the C89/C90 standard,
C needed to adapt to rapidly advancing hardware and compiler technologies.
This led to the release of a new standard, '''C99''', in 1999.

Key changes introduced in C99 include:
* Addition of <code>//</code> single-line comments (for C++ compatibility)
* Introduction of <code>inline</code> functions for performance optimization
* Support for Variable Length Arrays (VLA)
* New integer and complex types (<code>long long</code>, <code>_Complex</code>)
* Introduction of the <code>_Bool</code> type and <code>stdbool.h</code> header
* Provision of fixed-width integer types via <code>stdint.h</code> (e.g., <code>int32_t</code>)

During this era, C was widely used across embedded systems, network devices, and scientific computing,
establishing itself as an “industrial standard language.”

=== 2010s: Parallelism and Stability (C11, C17) ===
With the rise of multicore processors, C officially embraced parallel programming.
Released in 2011, '''C11''' became the first C standard to define a formal memory model and thread safety.

Core features of C11:
* Multithreading support (<code>_Thread_local</code>, <code>atomic</code> types)
* Static assertions (<code>_Static_assert</code>)
* Support for anonymous structs and unions
* Unicode expansion (<code>uchar.h</code>)
* Safer standard functions (<code>gets()</code> removed, <code>snprintf()</code> recommended)

C11 is widely regarded as the standard that defined “modern system-level C.”

In 2018, '''C17''' (ISO/IEC 9899:2018) was released,
not as a major feature update, but as a bug-fix and cleanup revision,
serving as a stable edition of C11.

=== 2020s: Modern Refinement (C23) ===
Published in 2023, '''C23''' preserves the 50-year-old philosophy of C
while incorporating select features from modern programming languages.

Major updates include:
* Introduction of the <code>nullptr</code> keyword (as a safer alternative to <code>NULL</code>)
* Standardization of UTF-8 string literals (<code>u8""</code>)
* Addition of the <code>typeof</code> operator and type inference expressions
* Support for <code>constexpr</code>-like constant evaluation
* Formal introduction of the <code>static_assert</code> syntax
* New <code>embed</code> directive for embedding binary data

C23 is regarded as “a practical evolution that modernizes C
without transforming it into an entirely new language,”
reflecting contemporary system and compiler design principles.

From its origins as the Unix development language in the 1970s
to its continued dominance in the 2020s,
C remains the '''standard language for operating systems, compilers, embedded systems, and hardware control'''.
Even after more than 50 years, its philosophy and structure have changed little,
and C continues to be “the simplest yet most fundamental programming language.”

== Philosophy ==
The design philosophy of C is not merely a collection of syntactic rules,
but rather a '''thought paradigm''' for understanding and manipulating computer hardware.
Dennis Ritchie defined C as a “machine-oriented high-level language,”
meaning that C is more than just a programming tool —
it represents a way of thinking about computers themselves.

The philosophy of C can be summarized in four core principles.

=== 1. Minimalism ===
C was designed under the principle of “providing only what is necessary.”
The language defines only a small set of core constructs,
leaving complex functionalities to be implemented directly by the programmer.
Automated abstractions such as garbage collection, classes, and exception handling
were deliberately excluded.

This philosophy grants programmers '''absolute freedom and responsibility''',
allowing powerful systems to be built from a small language core.
This design approach was later inherited by the [[Unix]] philosophy,
forming the basis of the principle “Do one thing and do it well.”

=== 2. Machine-Oriented Abstraction ===
C aims to be a high-level language capable of directly interacting with hardware.
This embodies the idea of '''“abstraction over machine code”''',
allowing programmers to control memory addresses, pointers, and register-level operations
without writing assembly code.

This concept goes beyond hardware-friendly syntax.
C encourages programmers to “understand the machine as it truly operates.”
Thus, C serves as a linguistic interface between hardware-level control
and higher-level logical structures.

=== 3. Portability and Implementation Freedom ===
C is a compiler-centered language —
that is, its implementation (the compiler) matters more than the language definition itself.
The language provides only minimal rules,
while compilers are responsible for adapting them to different platforms.

This structure realized the concept of “write once, run anywhere.”
One of C’s core ideas is that “a language should not be bound to a specific machine,”
which was the fundamental reason [[Unix]] could be ported across diverse hardware.

At the same time, C deliberately allows '''undefined behavior''',
maximizing compiler optimization and implementation freedom.
Although rare in modern languages,
this approach was key to preserving C’s performance and simplicity.

=== 4. Freedom and Responsibility ===
C gives nearly all control to the programmer.
Memory management, type casting, pointer arithmetic, and bit operations
are all left in the user’s hands.
Safety mechanisms are minimal,
and incorrect operations can immediately lead to crashes or undefined results.

This design reflects the philosophy of prioritizing “control over safety.”
C does not protect the programmer —
instead, it offers the same level of freedom as the machine itself.
This attitude solidified C’s identity as a “language equal to the machine.”

=== 5. Simplicity and Extensibility ===
C is simple, yet capable of expressing all forms of complexity.
Though the language is small, its composability allows developers to build
operating systems, compilers, graphics engines, and virtual machines.

This is why C is often described as “a small language, but a complete one.”
As Ritchie once said:
:''"C was not designed to hide the machine, but to express it efficiently."''

In other words, C’s simplicity is not a limitation of expression,
but a deliberate choice to maximize expressive efficiency.

=== 6. Philosophical Influence on Modern Languages ===
C’s philosophy became the foundational principle for many later languages:
* [[C++]] — added object-orientation and encapsulation atop C’s structure.
* [[Rust]] — inherited C’s performance and low-level control while reinforcing safety.
* [[Go]] — applied C’s simplicity and explicit control to modern system programming.
* [[Wave]] — reimagined and modernized C’s memory model and philosophy as a next-generation low-level language.

Thus, C has transcended its role as a language,
becoming the '''philosophical origin of programming languages'''.
Its core ideals — minimalism, portability, control, and simplicity —
remain the foundation of all modern system programming languages to this day.

== Key Features ==
C combines structural simplicity with low-level hardware control,
achieving both high performance and flexibility through the following technical features.

=== 1. Static Type System ===
In C, every variable’s data type must be explicitly declared at '''compile time'''.
This ensures predictable program behavior and allows the compiler
to determine memory size and operation methods in advance.

For example, operations between <code>int</code> and <code>float</code> are strictly distinguished at compile time,
executing without runtime overhead.
This '''statically analyzed design''' contrasts with modern dynamic languages,
enabling C to closely correspond to hardware operations.

C also supports both '''implicit casting''' and '''explicit casting''',
granting programmers full control over type conversions.
While powerful, these conversions may cause '''precision loss''' or '''overflow errors''' if misused.

=== 2. Pointers and Direct Memory Access ===
One of C’s most distinctive features is the concept of pointers.
A pointer holds a memory address as its value,
allowing direct reading and writing to memory regions.

<syntaxhighlight lang="c">
int a = 10;
int *p = &a;
printf("%d\n", *p); // prints 10
</syntaxhighlight>

Pointers are both the source of C’s power and its danger.
They enable indirect access to arrays, functions, and structures,
making them indispensable in low-level development such as kernels and drivers.

However, incorrect address access can cause a '''Segmentation Fault''',
which is why C is often described as an “unsafe but predictable” language.

=== 3. Manual Memory Management ===
C does not include garbage collection (GC).
Memory allocation and deallocation are entirely the programmer’s responsibility.

<syntaxhighlight lang="c">
int *arr = malloc(sizeof(int) * 5);
...
free(arr);
</syntaxhighlight>

Functions like <code>malloc()</code>, <code>calloc()</code>, <code>realloc()</code>, and <code>free()</code>
are defined in the standard library <code>stdlib.h</code>.
This manual management model offers '''maximum performance''',
but improper use can lead to '''memory leaks''' or '''double-free errors'''.

Unlike modern languages with automatic memory management,
C’s model reflects its philosophy of total system resource control.

=== 4. Preprocessor ===
Before actual compilation, the C compiler performs a '''preprocessing''' phase.
This processes directives beginning with the <code>#</code> symbol,
providing significant structural flexibility to the language.

Common preprocessor directives include:
* <code>#include</code> – include external header files
* <code>#define</code> – define macros
* <code>#ifdef</code>, <code>#ifndef</code>, <code>#endif</code> – conditional compilation

Although technically just text substitution,
the preprocessor provides flexibility for C’s build system
and is essential for managing platform-specific code in large projects.

=== 5. Structured Programming ===
C is a procedural language that adopts block structures to implement '''structured programming'''.
It organizes control flow into functions
and provides explicit structures using <code>if</code> statements, loops (<code>for</code>, <code>while</code>),
and the <code>switch</code> statement.

<syntaxhighlight lang="c">
for (int i = 0; i < 5; i++) {
printf("%d\n", i);
}
</syntaxhighlight>

This design improved readability and maintainability,
breaking away from the linear control flow of [[B language]] and [[assembly language]],
and establishing the concept of “logical program composition.”

Later languages such as [[Pascal]], [[C++]], and [[Rust]] inherited this paradigm.

=== 6. Function-Centric Architecture ===
C follows the rule that “all code executes within a function.”
Every executable program must have a <code>main()</code> function,
and all functions must declare explicit return types and parameter lists.

<syntaxhighlight lang="c">
int add(int a, int b) {
return a + b;
}
</syntaxhighlight>

Since C89, the function '''prototype''' format was introduced,
allowing compilers to check argument types and improve type safety at call time.

C’s function architecture influenced later developments such as
[[C++]] methods, [[Rust]]’s functional model, and [[Wave]]’s chain APIs.

=== 7. Platform Independence ===
C was designed with the principle of “not being tied to any machine.”
Instead of using assembly code specific to a CPU or OS,
it enables hardware-independent source code that compilers translate appropriately.

Portability is one of C’s defining features,
allowing the same code to be recompiled and run on Windows, Linux, macOS, Unix, and more.

This is made possible by features like <code>sizeof</code>, <code>typedef</code>,
and the <code>std*</code> family of types, which abstract differences in memory size across platforms.

=== 8. Standard Library ===
The C Standard Library is a core component that extends the language’s functionality.
It includes file I/O, string manipulation, mathematical operations, and memory management,
enabling basic system-level tasks without OS-specific calls.

Key header files include:
* <code>stdio.h</code> – standard input/output
* <code>stdlib.h</code> – memory management and utilities
* <code>string.h</code> – string operations
* <code>math.h</code> – mathematical functions
* <code>time.h</code> – time-related utilities

The standard library is defined by the ISO standard,
and all C implementations are required to support it.

=== 9. Combination of Efficiency and Simplicity ===
C merges near-hardware efficiency with a readable high-level syntax.
As a result, C programs are both fast and lightweight while remaining human-readable.

This balance is one of the main reasons C has endured for over half a century,
remaining the standard for operating systems, compilers, embedded systems,
and all environments where “performance is everything.”

=== 10. Undefined Behavior ===
C explicitly allows certain undefined behaviors,
leaving room for compiler optimization.

Examples include pointer access beyond memory bounds
or using uninitialized variables — both considered “undefined behavior.”
This flexibility grants compiler implementers freedom,
but introduces potential risks to program stability.

It is both the reason for C’s remarkable performance
and the reason it demands a high level of responsibility from its programmers.

== Basic Structure ==
C programs follow the structural principle that “all code executes within functions.”
The most important entry point is the <code>main()</code> function,
where the program’s execution begins and ends.

C has a modular architecture.
Each source file (<code>.c</code>) contains one or more functions,
and header files (<code>.h</code>) are used to share declarations and interfaces between modules.

Every C program consists of three main components:
# '''Preprocessing section''' – directives such as <code>#include</code> and <code>#define</code>.
# '''Function section''' – <code>main()</code> and user-defined functions.
# '''Data section''' – global variables, constants, and structure definitions.

The following is the simplest example of a C program structure:

<syntaxhighlight lang="c">
#include <stdio.h>

int main(void) {
printf("Hello, World!\n");
return 0;
}
</syntaxhighlight>

The <code>#include</code> directive instructs the preprocessor to include the standard library,
and the <code>main()</code> function serves as the program’s entry point.
The C compiler always looks for and begins execution from <code>main()</code>.
This structure was later inherited by [[C++]], [[Rust]], and [[Wave]].

The structural simplicity of C became a standard paradigm
for compiler design, operating system development, and embedded systems programming.

=== Data Types ===
C’s data types are directly linked to the hardware memory model.
Each data type explicitly defines its '''storage size''', '''signness''', and permissible operations,
which determine both performance and memory efficiency.

The basic data types are as follows:

{| class="wikitable"
! Category !! Type !! Typical Size !! Description
|-
| Integer || <code>char</code> || 1 byte || Character or 8-bit integer
|-
| Integer || <code>short</code> || 2 bytes || Small integer
|-
| Integer || <code>int</code> || 4 bytes || Standard integer type
|-
| Integer || <code>long</code> || 4–8 bytes || Large integer
|-
| Floating-point || <code>float</code> || 4 bytes || Single-precision float
|-
| Floating-point || <code>double</code> || 8 bytes || Double-precision float
|-
| Boolean || <code>_Bool</code> || 1 byte || Introduced in C99
|}

Starting with the C99 standard,
<code>stdint.h</code> introduced fixed-width integer types such as
<code>int8_t</code>, <code>int32_t</code>, and <code>uint64_t</code>,
ensuring consistency across platforms.

C also supports composite data types:
* <code>struct</code> – groups multiple variables into a single logical unit.
* <code>union</code> – allows different types to share the same memory space.
* <code>enum</code> – defines a set of named constants.
* <code>typedef</code> – assigns aliases to existing types.

Although simple, C’s type system enables highly efficient code generation
that maps closely to hardware architecture.

=== Control Statements ===
C’s control statements define the logical flow of program execution.
Conditionals and loops are high-level abstractions of assembly-level branch instructions,
forming the foundation of all imperative programming logic.

* Conditionals: <code>if</code>, <code>else if</code>, <code>else</code>
* Selection: <code>switch</code> / <code>case</code>
* Loops: <code>for</code>, <code>while</code>, <code>do-while</code>
* Flow control: <code>break</code>, <code>continue</code>, <code>goto</code>

Example:

<syntaxhighlight lang="c">
for (int i = 0; i < 5; i++) {
if (i == 3) continue;
printf("%d\n", i);
}
</syntaxhighlight>

C’s control statements not only branch logic flow,
but also define the conceptual structure of imperative programming.
Because these statements map directly to machine instructions,
they enable compilers to perform efficient low-level optimizations.

=== Memory and Pointers ===
At the heart of C lies the ability to “manipulate memory addresses.”
This capability is what makes C not just a high-level language,
but a true '''system language'''.

A pointer is a variable that stores a memory address,
allowing indirect access or modification of another variable’s value.

<syntaxhighlight lang="c">
int x = 42;
int *ptr = &x;
printf("%d\n", *ptr);
</syntaxhighlight>

Here, <code>&</code> is the address-of operator,
and <code>*</code> is the dereference operator.
Thus, <code>*ptr</code> reads the actual memory value of <code>x</code>.

Through pointer operations, C allows low-level control such as:
* Direct memory access and modification
* Efficient array and string handling
* Function pointers for callback implementations
* Dynamic memory allocation (<code>malloc()</code>, <code>free()</code>)

This structure made C the optimal language for developing
operating systems, drivers, and firmware — domains that require direct hardware control.
However, incorrect memory access can cause immediate program crashes,
a risk considered part of C’s core philosophy:
“with freedom comes responsibility.”

=== Compilation Process ===
C is a '''compiled language''', meaning source code must be translated
into machine code before execution.
The compilation process consists of four main stages:

# '''Preprocessing'''
Handles directives such as <code>#include</code> and <code>#define</code>,
performing conditional compilation and macro expansion.
# '''Compilation'''
Translates preprocessed code into assembly code,
performing syntax analysis, type checking, and optimization.
# '''Assembly'''
Converts assembly code into object files (<code>.o</code>).
# '''Linking'''
Combines multiple object files and libraries
into the final executable (<code>.exe</code> or ELF binary).

Example of a typical build process on Linux:

<syntaxhighlight lang="bash">
gcc -E main.c -o main.i # Preprocessing
gcc -S main.i -o main.s # Compilation
gcc -c main.s -o main.o # Assembly
gcc main.o -o main # Linking
</syntaxhighlight>

This multi-stage structure not only reflects C’s simplicity
but also served as the foundation model for [[compiler]] design.
Most modern compilers are built upon this architecture.

Throughout the entire process, C maintains its essence
as a language that expresses programs directly at the hardware level.
As a result, C enables efficient use of system resources
while allowing developers to write readable and structured code —
earning its reputation as a “machine-friendly high-level language.”

== Standard Macros ==
The C standard defines a set of '''predefined macros''' that every implementation (compiler) must provide.
These macros convey information about the compiler environment, standard version, and platform,
helping programs behave correctly across different systems.

Standard macros are recognized during the '''preprocessing stage''',
and are determined at '''compile time''', not at runtime.
In essence, the preprocessor in C functions as a “compiler–language interface” for environment metadata.

=== Major Macro List ===
The following table summarizes the representative macros defined by the ISO/IEC C standard and their purposes.

{| class="wikitable"
! Macro Name !! Description !! Introduced In
|-
| <code>__STDC__</code> ||
Indicates that the compiler conforms to the ANSI/ISO C standard.
A value of 1 signifies a standard-compliant implementation. || C89
|-
| <code>__STDC_VERSION__</code> ||
Specifies the supported version of the C standard.
Examples:
<code>199409L</code> → C94
<code>199901L</code> → C99
<code>201112L</code> → C11
<code>201710L</code> → C17
<code>202311L</code> → C23 || C90 and later
|-
| <code>__STDC_HOSTED__</code> ||
Indicates whether the environment is hosted (with standard library support)
or freestanding (independent, e.g., kernel or embedded).
1 = hosted, 0 = freestanding. || C99
|-
| <code>__FILE__</code> ||
String literal of the current source filename being compiled. || C89
|-
| <code>__LINE__</code> ||
Current line number in the source file. Useful for debugging and logging. || C89
|-
| <code>__DATE__</code> ||
Compilation date as a string (e.g., "Oct 17 2025"). || C89
|-
| <code>__TIME__</code> ||
Compilation time as a string (e.g., "14:30:42"). || C89
|-
| <code>__func__</code> ||
Returns the current function name as a string.
<syntaxhighlight lang="c">
void test() {
printf("%s\n", __func__);
}
</syntaxhighlight>
The above code prints "test". || C99
|-
| <code>__STDC_NO_ATOMICS__</code> ||
Defined as 1 if the compiler does not support <code>_Atomic</code>. || C11
|-
| <code>__STDC_NO_THREADS__</code> ||
Defined if the compiler does not support the standard threads library (<code>threads.h</code>). || C11
|-
| <code>__STDC_UTF_16__</code>, <code>__STDC_UTF_32__</code> ||
Indicates support for UTF-16 and UTF-32 character types. || C11
|-
| <code>__STDC_ANALYZABLE__</code> ||
Indicates whether static analysis features are supported. || C23
|-
| <code>__STDC_VERSION_STDINT_H__</code> ||
Specifies the version of <code>stdint.h</code>,
confirming support for standard integer types. || C23
|}

In addition to these, many compilers (e.g., GCC, Clang, MSVC)
provide their own proprietary extension macros.
For example, GCC defines <code>__GNUC__</code>, and MSVC defines <code>_MSC_VER</code>.

=== Role and Significance of Macros ===
Standard macros are not mere constants —
they serve as a '''linguistic interface between the compiler and the program'''.
By providing “compile-time environment information” rather than runtime data,
they allow conditional compilation and environment-specific behavior.

For instance, the following code performs compiler-specific conditional builds:

<syntaxhighlight lang="c">
#ifdef __GNUC__
printf("Compiled with GCC\n");
#elif defined(_MSC_VER)
printf("Compiled with MSVC\n");
#else
printf("Unknown compiler\n");
#endif
</syntaxhighlight>

This mechanism is one of the key reasons C achieves portability and implementation independence.
The source code remains identical,
but compilers can generate machine code tailored to their environments
by '''exposing system information through preprocessor macros'''.

=== Philosophical Aspect ===
C’s standard macro system is not merely an extension of preprocessing capabilities —
it embodies the language’s core philosophy:
'''“The language should be small, and the implementation should be powerful.”'''
The language defines only minimal promises,
delegating environmental awareness to the compiler through the preprocessor.

This design directly influenced the build systems and compiler metadata handling
in later languages such as [[C++]], [[Rust]], and [[Wave]].
In particular, the <code>build.meta</code> system in the Wave language
is considered an evolved form of C’s preprocessor macro concept.

Ultimately, standard macros serve as an intermediary layer
linking the language, compiler, and hardware —
the very mechanism that has allowed C to maintain its '''portability and implementation freedom'''
for over half a century.

== Influence on Other Languages ==
C became the foundation of nearly all major programming languages developed since the late 20th century.
Its influence extends far beyond syntax—encompassing philosophy, memory models, compiler design, and error-handling paradigms.
In other words, C did not merely shape “the form of languages” but “the way languages think.”

=== 1. Direct Descendant Languages ===
Languages that directly inherited C’s structure and syntax are collectively called the “C family.”
They evolved from C’s syntax, expression structure, and the concepts of pointers or references.

* '''C++''' — developed by [[Bjarne Stroustrup]] in 1983.
It extended C by adding classes, objects, inheritance, templates, and other
'''object-oriented''' features.
Maintaining backward compatibility with C,
C++ achieved both hardware-level control and high-level abstraction—
earning the title “the language that expanded C’s philosophy.”

* '''Objective-C''' — created in the 1980s by [[Brad Cox]] and [[Tom Love]].
It combined C syntax with Smalltalk’s message-passing paradigm.
It became the foundation for [[NeXTSTEP]], [[macOS]], and [[iOS]],
defining Apple’s entire software ecosystem.

* '''C#''' — designed by [[Anders Hejlsberg]] at [[Microsoft]].
Built on C/C++ syntax, it was made to operate within the .NET Framework.
It preserved C’s syntactic familiarity while introducing garbage collection and runtime safety.

* '''Java''' — simplified C++’s syntax and abstracted its memory model.
Although it runs entirely within a virtual machine,
its control structures, operators, and type system remain largely C-like.

All of these languages share the common goal of being “C-like but safer than C.”

=== 2. Indirect Influence (Structure and Philosophy) ===
C’s influence extends into language design philosophies as well.

* '''Rust''' — inherited C’s low-level control philosophy,
but introduced ownership and compile-time validation
to ensure memory safety.
It is often described as “C without undefined behavior.”

* '''Go''' — retained C’s simplicity and explicit control structures
while modernizing the model for concurrency and network programming.
Since [[Ken Thompson]] and [[Rob Pike]]—key C developers—were involved,
Go is regarded as a spiritual successor to C.

* '''D language''' — maintained the performance of C and C++
while integrating modern abstractions and managed memory.
Strong interoperability with C code is one of its core traits.

* '''Swift''' — Apple’s successor to Objective-C,
replacing the C-based runtime with a modern type system.
Yet, its ABI and runtime architecture remain deeply influenced by C.

* '''Wave''' — a next-generation system language
that fundamentally inherits C’s memory model and compiler philosophy,
removing unnecessary complexity while experimenting with new syntax structures.
It preserves C’s core concept of “machine-oriented abstraction.”

=== 3. Conceptual Influence Inside Languages ===
C’s legacy also extends deep into the internal structure of modern languages.

* '''Operator Semantics''' —
Most languages directly reuse C’s operator system.
Examples include <code>++</code>, <code>--</code>, <code>==</code>, <code>!=</code>, and <code>+=</code>.
This syntax has effectively become the “industry standard operator notation.”

* '''Standard Library Architecture''' —
The structure of C’s headers—<code>stdio</code>, <code>stdlib</code>, and <code>string</code>—
laid the groundwork for modern module and package systems.

* '''Compilation Model''' —
The pipeline of preprocessing → compilation → assembly → linking
was inherited by [[C++]], [[Objective-C]], [[Rust]], and [[Wave]].

* '''Undefined Behavior Concept''' —
A philosophical legacy of C.
Some languages have eliminated it entirely (Rust, Swift),
while others retain it in restricted form (C++, D).

=== 4. Influence on Programming Culture ===
C’s impact is not limited to technology—it shaped programming culture itself.

* The “Hello, World!” program tradition
originated from the textbook ''The C Programming Language''.

* The concept that “a function is the fundamental unit of a program”
became a universal assumption in language design after C.

* C’s syntax became the shared grammar of education, research, and industry.
Today, most programmers can learn new languages quickly
because they share C-style syntax.

=== 5. Philosophical Legacy ===
C is not merely a starting point for functionality—
it became the '''philosophical benchmark''' for language design.

Its influence continues along three fundamental axes:
* '''The Power of Simplicity''' — remove unnecessary abstractions and focus on essentials.
* '''Freedom of Control''' — programmers, not the language, govern memory.
* '''The Philosophy of Efficiency''' — extract performance directly from hardware.

This enduring spirit explains why all modern languages, no matter how advanced,
are still compared and analyzed against C.

Ultimately, C is more than a programming language—
it is the '''coordinate system of programming language history'''.
All languages can be classified as either “before C” or “after C.”

== Modern Evaluation ==
Although C was designed in the early 1970s,
it remains one of the most important system programming languages in the world even in the 2020s.
Its relevance is not merely as a “historical legacy,”
but because the very foundation of modern computing still rests upon it.

=== 1. Continuing Industrial Influence ===
Most operating systems, embedded firmware, compilers, network stacks,
and database engines are either written in C or deeply interconnected with it.
Notable examples include the [[Linux]] kernel, [[Windows]] NT kernel,
the Darwin layer of [[macOS]], [[PostgreSQL]], [[MySQL]], [[Redis]], and [[Nginx]].

These systems are not ordinary applications—
they form the '''core infrastructure of modern computing''' upon which all other software depends.
Thus, C serves as the “foundational language upon which all higher-level languages operate.”

Today, most hardware APIs and OS interfaces use
the C ABI (Application Binary Interface) as a standard.
This makes C not just a language but a '''common language of systems'''.

=== 2. Technical Strengths and Reasons for Survival ===
C has endured for over half a century due to several technical advantages:

* '''Deterministic Performance''' –
With no garbage collection or runtime management,
C provides fully predictable execution time and memory usage—
essential for real-time systems, embedded devices, and kernel programming.

* '''Direct Hardware Control''' –
Through pointers and bit-level operations,
C allows direct access to memory, registers, and hardware devices—
a capability no modern high-level language can fully replace.

* '''Simple Compilation Model''' –
The consistent pipeline of preprocessing → compilation → assembly → linking
avoids complex runtimes or virtual machines,
resulting in higher portability and reliability.

* '''Transparency''' –
C code maps closely to actual machine instructions,
allowing programmers to predict memory layout and execution flow at the assembly level.

In short, C continues to dominate in three domains:
'''performance, simplicity, and control.'''

=== 3. Limitations and Criticisms ===
Despite its power, C has inherent limitations when faced with modern requirements.

* '''Lack of Memory Safety''' —
While pointer arithmetic and manual memory management offer flexibility,
they also introduce critical vulnerabilities such as buffer overflows,
invalid references (segfaults), and use-after-free errors.
Many security issues in the 2020s still originate from C code.

* '''Undefined Behavior''' —
The C standard intentionally leaves certain behaviors undefined to enable optimization,
but this leads to inconsistent results and compiler-dependent behavior.

* '''Limited Expressiveness''' —
C lacks modern abstractions such as object orientation, generics, and exception handling.
Writing large-scale systems often requires auxiliary languages or frameworks.

* '''Low Developer Productivity''' —
Manual memory management, pointer handling, and difficult debugging
make C less suitable for large-scale application development,
where speed of development and maintainability are key.

For these reasons, C is no longer a “universal language.”
Successor system languages such as [[Rust]], [[Go]], and [[Wave]]
have emerged to pursue both safety and efficiency simultaneously.

=== 4. Educational and Philosophical Value ===
Nevertheless, C remains the '''core language of computer science education'''.
This is not simply due to tradition—
C most directly reveals “how computers truly work.”

Learning C means learning memory structure, pointers, compiler mechanics,
and CPU instruction models.
Thus, universities, research institutes, and corporate training programs worldwide
continue to teach C as “the language upon which all others are built.”

From a philosophical standpoint,
C embodies the principle that “humans should master the machine, not be protected from it.”
Even as modern languages pursue automation and abstraction,
this philosophy explains why C endures.

=== 5. C’s Current Role ===
Today, C is no longer a language of rapid innovation.
Instead, it is valued for its “unchanging stability” and “established ecosystem.”
C does not aim to reinvent itself like modern languages;
most updates focus on refinement and standardization.

Since the [[C23]] standard, C continues to thrive alongside
advanced compiler infrastructures such as [[LLVM]], [[GCC]], and [[Clang]],
remaining the dominant language for kernels, networking, hardware control, and real-time systems. Its role has shifted from “competitor among new languages”
to the enduring '''reference language for all others.'''

=== 6. Overall Evaluation ===
C remains both the foundation of modern software
and the philosophical axis of programming languages.
Its simplicity and risk are its greatest strengths,
and in terms of performance and control, it remains nearly unrivaled.

Ultimately, C is “an imperfect but fully comprehensible language,”
one that continues to define the very history of technology itself.

:''"C is both the origin and the gravity of programming languages."'' — TechPedia Editorial

== Implementation ==

=== The First C Compiler ===
The first C compiler had no official name and was developed by '''Dennis Ritchie'''. It was created around '''1972''', during the early days of the Unix system on the [[PDP-11]] platform. At that time, the compiler was implemented in [[Assembly language]] and functioned as a '''simple one-pass compiler''' that translated high-level code directly into machine code.

This early version was evolved from the [[B]] compiler, and as the C language itself stabilized, '''Dennis Ritchie rewrote the compiler in C''', achieving a '''fully [[Self hosting|self-hosting]]'''self-hosting '''environment'''. This process is considered a '''milestone in modern programming language development''', marking the '''first instance of a language capable of compiling itself'''. As a result, this compiler enabled the [[Unix]] '''kernel''' and its core utilities to be rewritten in C, laying the '''foundation for most modern system programming languages'''.

The source code he wrote in C is known as [https://github.com/LunaStev/legacy-cc legacy-cc]

=== Compiler ===

* [[GNU Compiler Collection]]
* [[LLVM|Clang / LLVM]]
* [[Microsoft Visual C++]]
* [[TinyCC]]
* [[Portable C Compiler]]
* [[Local C Compiler]]
* [[Small Device C Compiler]]
* [[Intel C Compiler]]
* [[Watcom C Compiler]]
* [[Borland Turbo C / C++]]
* [[Comeau C/C++]]
* [[LCC-Win32]]
* [[cproc]]
* [[8cc]]
* [[chibicc]]
* [[pcc68k]]
* [[vbcc]]
* [[cfront]]

=== Interpreter ===

* [[CINT]]
* [[Ch Interpreter]]
* [[Cling]]
* [[C-REPL]]
* [[CSharpRepl]]

== Related Articles ==
* [[Programming language]]
* [[B]]
* [[C++]]
* [[Rust]]
* [[Wave]]
* [[Assembly language]]
* [[Compiler]]
* [[Operating system]]
* [[Unix]]

== References ==
* Dennis M. Ritchie & Brian W. Kernighan, ''The C Programming Language'', Prentice Hall, 1978.
* ISO/IEC 9899:2023 – Information technology — Programming languages — C (C23 Standard).
* ISO/IEC JTC1/SC22/WG14, [https://www.open-std.org/jtc1/sc22/wg14/ Official C Language Standard Committee Website].
* Bell Labs Computer Science Research Center, ''The Development of the C Language'', Dennis Ritchie, 1993.
* Bjarne Stroustrup, ''A History of C++: 1979–1991'', ACM SIGPLAN Notices, Vol. 28, No. 3, 1993.
* GNU Project, [https://gcc.gnu.org GCC (GNU Compiler Collection) Documentation].
* Clang Project, [https://clang.llvm.org Clang: C Language Family Frontend for LLVM].

[[Category:Programming languages]]
[[Category:C family]]
[[Category:System programming]]
[[Category:1970s software]]

C

2025-10-17T07:26:44Z

LunaStev:

{{Software infobox
| Name = C
| Logo = [[File:C_logo.png|120px]]
| Developer = Dennis Ritchie
| Released = 1972
| Latest release= C17 (2018)
| Extensions = .c, .h
| License = ISO/IEC 9899
| Website = https://www.open-std.org/jtc1/sc22/wg14/
}}

== Overview ==
'''C''' is a general-purpose programming language developed by '''Dennis Ritchie''' in the early 1970s at [[Bell Labs]].
At that time, Bell Labs — led by [[Ken Thompson]] and Ritchie — was developing a new operating system called [[Unix]],
and during this process, the limitations of assembly-based systems became apparent.

In the early 1970s, every computer had its own unique instruction set,
and porting an operating system or compiler required rewriting the entire codebase.
To solve this problem, Bell Labs set a goal to create a '''“portable operating system”''',
and to achieve this, they needed a new language that preserved the low-level control of assembly
while providing the structural expressiveness of a high-level language.

It was in this context that C was born.
Ritchie improved upon [[B]], originally developed by Thompson,
introducing a more efficient and machine-friendly design.
C was first completed in 1972, and by 1973, the entire Unix kernel was successfully rewritten in C.
This event marked a major turning point in computer science history,
establishing C as a “system-level language.”

The greatest innovation of C lies in its philosophy as a '''“machine-oriented high-level language.”'''
This concept balances performance and abstraction
by allowing direct hardware control while organizing code
into functions and logical blocks.

C was designed around the following technical principles and philosophies:
* '''Low-level accessibility''' — direct memory manipulation via pointers (<code>*</code>) and the address operator (<code>&</code>).
* '''High-level structuring''' — logical code organization using conditionals, loops, functions, and structures.
* '''Minimalism''' — exclusion of unnecessary syntax, providing flexibility through simplicity.
* '''Portability''' — independence from specific hardware, enabling recompilation on different architectures.

Furthermore, C allows explicit hardware control
while maintaining simplicity and readability suitable for human developers.
Thanks to this balance, C became a foundational language across nearly all domains —
including compilers, operating systems, embedded systems, databases, and game engines.

The structural simplicity of C influenced the design of countless later languages.
[[C++]], [[Objective-C]], [[C#]], [[Rust]], [[Go]], and [[Wave]]
inherit and extend C’s syntax, memory model, function structure, and control flow.
As a result, C is regarded not merely as a language but as
an '''architectural prototype of programming language design.'''

Even today, C continues to serve as the standard for new language and system design,
remaining indispensable in operating system development, microcontroller programming,
and modern runtime implementations.
Its philosophical essence can be summarized by the following statement:

''“C is not just a programming language; it is a way of thinking about machines.”'' — Dennis Ritchie

== History ==
The evolution of C is not merely a story of syntax changes,
but a process intertwined with the development of operating systems, compilers, and hardware architecture.
Since its birth in the early 1970s, C has undergone several rounds of standardization,
laying the foundation for modern programming language design.

=== 1970s: Birth and Establishment ===
C was developed in 1972 at [[Bell Labs]] by '''Dennis Ritchie'''.
It was influenced by [[B]] and [[BCPL]],
and designed to efficiently implement the [[Unix]] kernel on the PDP-11 computer system.

In 1973, when the Unix kernel was largely rewritten in C,
it became the first language to enable a “machine-independent operating system implementation.”
This milestone introduced the concept of portability to the software industry.

In 1978, Ritchie and [[Brian W. Kernighan]] published
''The C Programming Language'' (commonly known as '''K&R C''').
The book became a de facto standard,
and compiler developers worldwide used it as the basis for C implementations.

=== 1980s: The Beginning of Standardization (ANSI C) ===
As C was used across different environments,
syntax discrepancies between compilers grew significantly,
creating the need for standardization.

In 1983, the '''ANSI X3J11 Committee''' was formed
to establish an official standard specification,
and in 1989, the American National Standards Institute (ANSI) approved it.

This standard, known as '''ANSI X3.159-1989''', or simply '''ANSI C''' or '''C89''',
included the following major changes:
* Clear definition of function declaration format (prototype introduction)
* Addition of standard libraries <code>stdlib.h</code>, <code>string.h</code>, <code>assert.h</code>
* Improvements to enumerations (<code>enum</code>) and constant expressions
* Establishment of a standard I/O model (<code>stdio.h</code>)

ANSI C was later adopted as an international standard by ISO in 1990,
becoming '''ISO/IEC 9899:1990''', also known as '''C90'''.

=== 1990s: The Foundation of Modern Syntax (C99) ===
After the publication of the C89/C90 standard,
C needed to adapt to rapidly advancing hardware and compiler technologies.
This led to the release of a new standard, '''C99''', in 1999.

Key changes introduced in C99 include:
* Addition of <code>//</code> single-line comments (for C++ compatibility)
* Introduction of <code>inline</code> functions for performance optimization
* Support for Variable Length Arrays (VLA)
* New integer and complex types (<code>long long</code>, <code>_Complex</code>)
* Introduction of the <code>_Bool</code> type and <code>stdbool.h</code> header
* Provision of fixed-width integer types via <code>stdint.h</code> (e.g., <code>int32_t</code>)

During this era, C was widely used across embedded systems, network devices, and scientific computing,
establishing itself as an “industrial standard language.”

=== 2010s: Parallelism and Stability (C11, C17) ===
With the rise of multicore processors, C officially embraced parallel programming.
Released in 2011, '''C11''' became the first C standard to define a formal memory model and thread safety.

Core features of C11:
* Multithreading support (<code>_Thread_local</code>, <code>atomic</code> types)
* Static assertions (<code>_Static_assert</code>)
* Support for anonymous structs and unions
* Unicode expansion (<code>uchar.h</code>)
* Safer standard functions (<code>gets()</code> removed, <code>snprintf()</code> recommended)

C11 is widely regarded as the standard that defined “modern system-level C.”

In 2018, '''C17''' (ISO/IEC 9899:2018) was released,
not as a major feature update, but as a bug-fix and cleanup revision,
serving as a stable edition of C11.

=== 2020s: Modern Refinement (C23) ===
Published in 2023, '''C23''' preserves the 50-year-old philosophy of C
while incorporating select features from modern programming languages.

Major updates include:
* Introduction of the <code>nullptr</code> keyword (as a safer alternative to <code>NULL</code>)
* Standardization of UTF-8 string literals (<code>u8""</code>)
* Addition of the <code>typeof</code> operator and type inference expressions
* Support for <code>constexpr</code>-like constant evaluation
* Formal introduction of the <code>static_assert</code> syntax
* New <code>embed</code> directive for embedding binary data

C23 is regarded as “a practical evolution that modernizes C
without transforming it into an entirely new language,”
reflecting contemporary system and compiler design principles.

From its origins as the Unix development language in the 1970s
to its continued dominance in the 2020s,
C remains the '''standard language for operating systems, compilers, embedded systems, and hardware control'''.
Even after more than 50 years, its philosophy and structure have changed little,
and C continues to be “the simplest yet most fundamental programming language.”

== Philosophy ==
The design philosophy of C is not merely a collection of syntactic rules,
but rather a '''thought paradigm''' for understanding and manipulating computer hardware.
Dennis Ritchie defined C as a “machine-oriented high-level language,”
meaning that C is more than just a programming tool —
it represents a way of thinking about computers themselves.

The philosophy of C can be summarized in four core principles.

=== 1. Minimalism ===
C was designed under the principle of “providing only what is necessary.”
The language defines only a small set of core constructs,
leaving complex functionalities to be implemented directly by the programmer.
Automated abstractions such as garbage collection, classes, and exception handling
were deliberately excluded.

This philosophy grants programmers '''absolute freedom and responsibility''',
allowing powerful systems to be built from a small language core.
This design approach was later inherited by the [[Unix]] philosophy,
forming the basis of the principle “Do one thing and do it well.”

=== 2. Machine-Oriented Abstraction ===
C aims to be a high-level language capable of directly interacting with hardware.
This embodies the idea of '''“abstraction over machine code”''',
allowing programmers to control memory addresses, pointers, and register-level operations
without writing assembly code.

This concept goes beyond hardware-friendly syntax.
C encourages programmers to “understand the machine as it truly operates.”
Thus, C serves as a linguistic interface between hardware-level control
and higher-level logical structures.

=== 3. Portability and Implementation Freedom ===
C is a compiler-centered language —
that is, its implementation (the compiler) matters more than the language definition itself.
The language provides only minimal rules,
while compilers are responsible for adapting them to different platforms.

This structure realized the concept of “write once, run anywhere.”
One of C’s core ideas is that “a language should not be bound to a specific machine,”
which was the fundamental reason [[Unix]] could be ported across diverse hardware.

At the same time, C deliberately allows '''undefined behavior''',
maximizing compiler optimization and implementation freedom.
Although rare in modern languages,
this approach was key to preserving C’s performance and simplicity.

=== 4. Freedom and Responsibility ===
C gives nearly all control to the programmer.
Memory management, type casting, pointer arithmetic, and bit operations
are all left in the user’s hands.
Safety mechanisms are minimal,
and incorrect operations can immediately lead to crashes or undefined results.

This design reflects the philosophy of prioritizing “control over safety.”
C does not protect the programmer —
instead, it offers the same level of freedom as the machine itself.
This attitude solidified C’s identity as a “language equal to the machine.”

=== 5. Simplicity and Extensibility ===
C is simple, yet capable of expressing all forms of complexity.
Though the language is small, its composability allows developers to build
operating systems, compilers, graphics engines, and virtual machines.

This is why C is often described as “a small language, but a complete one.”
As Ritchie once said:
:''"C was not designed to hide the machine, but to express it efficiently."''

In other words, C’s simplicity is not a limitation of expression,
but a deliberate choice to maximize expressive efficiency.

=== 6. Philosophical Influence on Modern Languages ===
C’s philosophy became the foundational principle for many later languages:
* [[C++]] — added object-orientation and encapsulation atop C’s structure.
* [[Rust]] — inherited C’s performance and low-level control while reinforcing safety.
* [[Go]] — applied C’s simplicity and explicit control to modern system programming.
* [[Wave]] — reimagined and modernized C’s memory model and philosophy as a next-generation low-level language.

Thus, C has transcended its role as a language,
becoming the '''philosophical origin of programming languages'''.
Its core ideals — minimalism, portability, control, and simplicity —
remain the foundation of all modern system programming languages to this day.

== Key Features ==
C combines structural simplicity with low-level hardware control,
achieving both high performance and flexibility through the following technical features.

=== 1. Static Type System ===
In C, every variable’s data type must be explicitly declared at '''compile time'''.
This ensures predictable program behavior and allows the compiler
to determine memory size and operation methods in advance.

For example, operations between <code>int</code> and <code>float</code> are strictly distinguished at compile time,
executing without runtime overhead.
This '''statically analyzed design''' contrasts with modern dynamic languages,
enabling C to closely correspond to hardware operations.

C also supports both '''implicit casting''' and '''explicit casting''',
granting programmers full control over type conversions.
While powerful, these conversions may cause '''precision loss''' or '''overflow errors''' if misused.

=== 2. Pointers and Direct Memory Access ===
One of C’s most distinctive features is the concept of pointers.
A pointer holds a memory address as its value,
allowing direct reading and writing to memory regions.

<syntaxhighlight lang="c">
int a = 10;
int *p = &a;
printf("%d\n", *p); // prints 10
</syntaxhighlight>

Pointers are both the source of C’s power and its danger.
They enable indirect access to arrays, functions, and structures,
making them indispensable in low-level development such as kernels and drivers.

However, incorrect address access can cause a '''Segmentation Fault''',
which is why C is often described as an “unsafe but predictable” language.

=== 3. Manual Memory Management ===
C does not include garbage collection (GC).
Memory allocation and deallocation are entirely the programmer’s responsibility.

<syntaxhighlight lang="c">
int *arr = malloc(sizeof(int) * 5);
...
free(arr);
</syntaxhighlight>

Functions like <code>malloc()</code>, <code>calloc()</code>, <code>realloc()</code>, and <code>free()</code>
are defined in the standard library <code>stdlib.h</code>.
This manual management model offers '''maximum performance''',
but improper use can lead to '''memory leaks''' or '''double-free errors'''.

Unlike modern languages with automatic memory management,
C’s model reflects its philosophy of total system resource control.

=== 4. Preprocessor ===
Before actual compilation, the C compiler performs a '''preprocessing''' phase.
This processes directives beginning with the <code>#</code> symbol,
providing significant structural flexibility to the language.

Common preprocessor directives include:
* <code>#include</code> – include external header files
* <code>#define</code> – define macros
* <code>#ifdef</code>, <code>#ifndef</code>, <code>#endif</code> – conditional compilation

Although technically just text substitution,
the preprocessor provides flexibility for C’s build system
and is essential for managing platform-specific code in large projects.

=== 5. Structured Programming ===
C is a procedural language that adopts block structures to implement '''structured programming'''.
It organizes control flow into functions
and provides explicit structures using <code>if</code> statements, loops (<code>for</code>, <code>while</code>),
and the <code>switch</code> statement.

<syntaxhighlight lang="c">
for (int i = 0; i < 5; i++) {
printf("%d\n", i);
}
</syntaxhighlight>

This design improved readability and maintainability,
breaking away from the linear control flow of [[B language]] and [[assembly language]],
and establishing the concept of “logical program composition.”

Later languages such as [[Pascal]], [[C++]], and [[Rust]] inherited this paradigm.

=== 6. Function-Centric Architecture ===
C follows the rule that “all code executes within a function.”
Every executable program must have a <code>main()</code> function,
and all functions must declare explicit return types and parameter lists.

<syntaxhighlight lang="c">
int add(int a, int b) {
return a + b;
}
</syntaxhighlight>

Since C89, the function '''prototype''' format was introduced,
allowing compilers to check argument types and improve type safety at call time.

C’s function architecture influenced later developments such as
[[C++]] methods, [[Rust]]’s functional model, and [[Wave]]’s chain APIs.

=== 7. Platform Independence ===
C was designed with the principle of “not being tied to any machine.”
Instead of using assembly code specific to a CPU or OS,
it enables hardware-independent source code that compilers translate appropriately.

Portability is one of C’s defining features,
allowing the same code to be recompiled and run on Windows, Linux, macOS, Unix, and more.

This is made possible by features like <code>sizeof</code>, <code>typedef</code>,
and the <code>std*</code> family of types, which abstract differences in memory size across platforms.

=== 8. Standard Library ===
The C Standard Library is a core component that extends the language’s functionality.
It includes file I/O, string manipulation, mathematical operations, and memory management,
enabling basic system-level tasks without OS-specific calls.

Key header files include:
* <code>stdio.h</code> – standard input/output
* <code>stdlib.h</code> – memory management and utilities
* <code>string.h</code> – string operations
* <code>math.h</code> – mathematical functions
* <code>time.h</code> – time-related utilities

The standard library is defined by the ISO standard,
and all C implementations are required to support it.

=== 9. Combination of Efficiency and Simplicity ===
C merges near-hardware efficiency with a readable high-level syntax.
As a result, C programs are both fast and lightweight while remaining human-readable.

This balance is one of the main reasons C has endured for over half a century,
remaining the standard for operating systems, compilers, embedded systems,
and all environments where “performance is everything.”

=== 10. Undefined Behavior ===
C explicitly allows certain undefined behaviors,
leaving room for compiler optimization.

Examples include pointer access beyond memory bounds
or using uninitialized variables — both considered “undefined behavior.”
This flexibility grants compiler implementers freedom,
but introduces potential risks to program stability.

It is both the reason for C’s remarkable performance
and the reason it demands a high level of responsibility from its programmers.

== Basic Structure ==
C programs follow the structural principle that “all code executes within functions.”
The most important entry point is the <code>main()</code> function,
where the program’s execution begins and ends.

C has a modular architecture.
Each source file (<code>.c</code>) contains one or more functions,
and header files (<code>.h</code>) are used to share declarations and interfaces between modules.

Every C program consists of three main components:
# '''Preprocessing section''' – directives such as <code>#include</code> and <code>#define</code>.
# '''Function section''' – <code>main()</code> and user-defined functions.
# '''Data section''' – global variables, constants, and structure definitions.

The following is the simplest example of a C program structure:

<syntaxhighlight lang="c">
#include <stdio.h>

int main(void) {
printf("Hello, World!\n");
return 0;
}
</syntaxhighlight>

The <code>#include</code> directive instructs the preprocessor to include the standard library,
and the <code>main()</code> function serves as the program’s entry point.
The C compiler always looks for and begins execution from <code>main()</code>.
This structure was later inherited by [[C++]], [[Rust]], and [[Wave]].

The structural simplicity of C became a standard paradigm
for compiler design, operating system development, and embedded systems programming.

=== Data Types ===
C’s data types are directly linked to the hardware memory model.
Each data type explicitly defines its '''storage size''', '''signness''', and permissible operations,
which determine both performance and memory efficiency.

The basic data types are as follows:

{| class="wikitable"
! Category !! Type !! Typical Size !! Description
|-
| Integer || <code>char</code> || 1 byte || Character or 8-bit integer
|-
| Integer || <code>short</code> || 2 bytes || Small integer
|-
| Integer || <code>int</code> || 4 bytes || Standard integer type
|-
| Integer || <code>long</code> || 4–8 bytes || Large integer
|-
| Floating-point || <code>float</code> || 4 bytes || Single-precision float
|-
| Floating-point || <code>double</code> || 8 bytes || Double-precision float
|-
| Boolean || <code>_Bool</code> || 1 byte || Introduced in C99
|}

Starting with the C99 standard,
<code>stdint.h</code> introduced fixed-width integer types such as
<code>int8_t</code>, <code>int32_t</code>, and <code>uint64_t</code>,
ensuring consistency across platforms.

C also supports composite data types:
* <code>struct</code> – groups multiple variables into a single logical unit.
* <code>union</code> – allows different types to share the same memory space.
* <code>enum</code> – defines a set of named constants.
* <code>typedef</code> – assigns aliases to existing types.

Although simple, C’s type system enables highly efficient code generation
that maps closely to hardware architecture.

=== Control Statements ===
C’s control statements define the logical flow of program execution.
Conditionals and loops are high-level abstractions of assembly-level branch instructions,
forming the foundation of all imperative programming logic.

* Conditionals: <code>if</code>, <code>else if</code>, <code>else</code>
* Selection: <code>switch</code> / <code>case</code>
* Loops: <code>for</code>, <code>while</code>, <code>do-while</code>
* Flow control: <code>break</code>, <code>continue</code>, <code>goto</code>

Example:

<syntaxhighlight lang="c">
for (int i = 0; i < 5; i++) {
if (i == 3) continue;
printf("%d\n", i);
}
</syntaxhighlight>

C’s control statements not only branch logic flow,
but also define the conceptual structure of imperative programming.
Because these statements map directly to machine instructions,
they enable compilers to perform efficient low-level optimizations.

=== Memory and Pointers ===
At the heart of C lies the ability to “manipulate memory addresses.”
This capability is what makes C not just a high-level language,
but a true '''system language'''.

A pointer is a variable that stores a memory address,
allowing indirect access or modification of another variable’s value.

<syntaxhighlight lang="c">
int x = 42;
int *ptr = &x;
printf("%d\n", *ptr);
</syntaxhighlight>

Here, <code>&</code> is the address-of operator,
and <code>*</code> is the dereference operator.
Thus, <code>*ptr</code> reads the actual memory value of <code>x</code>.

Through pointer operations, C allows low-level control such as:
* Direct memory access and modification
* Efficient array and string handling
* Function pointers for callback implementations
* Dynamic memory allocation (<code>malloc()</code>, <code>free()</code>)

This structure made C the optimal language for developing
operating systems, drivers, and firmware — domains that require direct hardware control.
However, incorrect memory access can cause immediate program crashes,
a risk considered part of C’s core philosophy:
“with freedom comes responsibility.”

=== Compilation Process ===
C is a '''compiled language''', meaning source code must be translated
into machine code before execution.
The compilation process consists of four main stages:

# '''Preprocessing'''
Handles directives such as <code>#include</code> and <code>#define</code>,
performing conditional compilation and macro expansion.
# '''Compilation'''
Translates preprocessed code into assembly code,
performing syntax analysis, type checking, and optimization.
# '''Assembly'''
Converts assembly code into object files (<code>.o</code>).
# '''Linking'''
Combines multiple object files and libraries
into the final executable (<code>.exe</code> or ELF binary).

Example of a typical build process on Linux:

<syntaxhighlight lang="bash">
gcc -E main.c -o main.i # Preprocessing
gcc -S main.i -o main.s # Compilation
gcc -c main.s -o main.o # Assembly
gcc main.o -o main # Linking
</syntaxhighlight>

This multi-stage structure not only reflects C’s simplicity
but also served as the foundation model for [[compiler]] design.
Most modern compilers are built upon this architecture.

Throughout the entire process, C maintains its essence
as a language that expresses programs directly at the hardware level.
As a result, C enables efficient use of system resources
while allowing developers to write readable and structured code —
earning its reputation as a “machine-friendly high-level language.”

== Standard Macros ==
The C standard defines a set of '''predefined macros''' that every implementation (compiler) must provide.
These macros convey information about the compiler environment, standard version, and platform,
helping programs behave correctly across different systems.

Standard macros are recognized during the '''preprocessing stage''',
and are determined at '''compile time''', not at runtime.
In essence, the preprocessor in C functions as a “compiler–language interface” for environment metadata.

=== Major Macro List ===
The following table summarizes the representative macros defined by the ISO/IEC C standard and their purposes.

{| class="wikitable"
! Macro Name !! Description !! Introduced In
|-
| <code>__STDC__</code> ||
Indicates that the compiler conforms to the ANSI/ISO C standard.
A value of 1 signifies a standard-compliant implementation. || C89
|-
| <code>__STDC_VERSION__</code> ||
Specifies the supported version of the C standard.
Examples:
<code>199409L</code> → C94
<code>199901L</code> → C99
<code>201112L</code> → C11
<code>201710L</code> → C17
<code>202311L</code> → C23 || C90 and later
|-
| <code>__STDC_HOSTED__</code> ||
Indicates whether the environment is hosted (with standard library support)
or freestanding (independent, e.g., kernel or embedded).
1 = hosted, 0 = freestanding. || C99
|-
| <code>__FILE__</code> ||
String literal of the current source filename being compiled. || C89
|-
| <code>__LINE__</code> ||
Current line number in the source file. Useful for debugging and logging. || C89
|-
| <code>__DATE__</code> ||
Compilation date as a string (e.g., "Oct 17 2025"). || C89
|-
| <code>__TIME__</code> ||
Compilation time as a string (e.g., "14:30:42"). || C89
|-
| <code>__func__</code> ||
Returns the current function name as a string.
<syntaxhighlight lang="c">
void test() {
printf("%s\n", __func__);
}
</syntaxhighlight>
The above code prints "test". || C99
|-
| <code>__STDC_NO_ATOMICS__</code> ||
Defined as 1 if the compiler does not support <code>_Atomic</code>. || C11
|-
| <code>__STDC_NO_THREADS__</code> ||
Defined if the compiler does not support the standard threads library (<code>threads.h</code>). || C11
|-
| <code>__STDC_UTF_16__</code>, <code>__STDC_UTF_32__</code> ||
Indicates support for UTF-16 and UTF-32 character types. || C11
|-
| <code>__STDC_ANALYZABLE__</code> ||
Indicates whether static analysis features are supported. || C23
|-
| <code>__STDC_VERSION_STDINT_H__</code> ||
Specifies the version of <code>stdint.h</code>,
confirming support for standard integer types. || C23
|}

In addition to these, many compilers (e.g., GCC, Clang, MSVC)
provide their own proprietary extension macros.
For example, GCC defines <code>__GNUC__</code>, and MSVC defines <code>_MSC_VER</code>.

=== Role and Significance of Macros ===
Standard macros are not mere constants —
they serve as a '''linguistic interface between the compiler and the program'''.
By providing “compile-time environment information” rather than runtime data,
they allow conditional compilation and environment-specific behavior.

For instance, the following code performs compiler-specific conditional builds:

<syntaxhighlight lang="c">
#ifdef __GNUC__
printf("Compiled with GCC\n");
#elif defined(_MSC_VER)
printf("Compiled with MSVC\n");
#else
printf("Unknown compiler\n");
#endif
</syntaxhighlight>

This mechanism is one of the key reasons C achieves portability and implementation independence.
The source code remains identical,
but compilers can generate machine code tailored to their environments
by '''exposing system information through preprocessor macros'''.

=== Philosophical Aspect ===
C’s standard macro system is not merely an extension of preprocessing capabilities —
it embodies the language’s core philosophy:
'''“The language should be small, and the implementation should be powerful.”'''
The language defines only minimal promises,
delegating environmental awareness to the compiler through the preprocessor.

This design directly influenced the build systems and compiler metadata handling
in later languages such as [[C++]], [[Rust]], and [[Wave]].
In particular, the <code>build.meta</code> system in the Wave language
is considered an evolved form of C’s preprocessor macro concept.

Ultimately, standard macros serve as an intermediary layer
linking the language, compiler, and hardware —
the very mechanism that has allowed C to maintain its '''portability and implementation freedom'''
for over half a century.

== Influence on Other Languages ==
C became the foundation of nearly all major programming languages developed since the late 20th century.
Its influence extends far beyond syntax—encompassing philosophy, memory models, compiler design, and error-handling paradigms.
In other words, C did not merely shape “the form of languages” but “the way languages think.”

=== 1. Direct Descendant Languages ===
Languages that directly inherited C’s structure and syntax are collectively called the “C family.”
They evolved from C’s syntax, expression structure, and the concepts of pointers or references.

* '''C++''' — developed by [[Bjarne Stroustrup]] in 1983.
It extended C by adding classes, objects, inheritance, templates, and other
'''object-oriented''' features.
Maintaining backward compatibility with C,
C++ achieved both hardware-level control and high-level abstraction—
earning the title “the language that expanded C’s philosophy.”

* '''Objective-C''' — created in the 1980s by [[Brad Cox]] and [[Tom Love]].
It combined C syntax with Smalltalk’s message-passing paradigm.
It became the foundation for [[NeXTSTEP]], [[macOS]], and [[iOS]],
defining Apple’s entire software ecosystem.

* '''C#''' — designed by [[Anders Hejlsberg]] at [[Microsoft]].
Built on C/C++ syntax, it was made to operate within the .NET Framework.
It preserved C’s syntactic familiarity while introducing garbage collection and runtime safety.

* '''Java''' — simplified C++’s syntax and abstracted its memory model.
Although it runs entirely within a virtual machine,
its control structures, operators, and type system remain largely C-like.

All of these languages share the common goal of being “C-like but safer than C.”

=== 2. Indirect Influence (Structure and Philosophy) ===
C’s influence extends into language design philosophies as well.

* '''Rust''' — inherited C’s low-level control philosophy,
but introduced ownership and compile-time validation
to ensure memory safety.
It is often described as “C without undefined behavior.”

* '''Go''' — retained C’s simplicity and explicit control structures
while modernizing the model for concurrency and network programming.
Since [[Ken Thompson]] and [[Rob Pike]]—key C developers—were involved,
Go is regarded as a spiritual successor to C.

* '''D language''' — maintained the performance of C and C++
while integrating modern abstractions and managed memory.
Strong interoperability with C code is one of its core traits.

* '''Swift''' — Apple’s successor to Objective-C,
replacing the C-based runtime with a modern type system.
Yet, its ABI and runtime architecture remain deeply influenced by C.

* '''Wave''' — a next-generation system language
that fundamentally inherits C’s memory model and compiler philosophy,
removing unnecessary complexity while experimenting with new syntax structures.
It preserves C’s core concept of “machine-oriented abstraction.”

=== 3. Conceptual Influence Inside Languages ===
C’s legacy also extends deep into the internal structure of modern languages.

* '''Operator Semantics''' —
Most languages directly reuse C’s operator system.
Examples include <code>++</code>, <code>--</code>, <code>==</code>, <code>!=</code>, and <code>+=</code>.
This syntax has effectively become the “industry standard operator notation.”

* '''Standard Library Architecture''' —
The structure of C’s headers—<code>stdio</code>, <code>stdlib</code>, and <code>string</code>—
laid the groundwork for modern module and package systems.

* '''Compilation Model''' —
The pipeline of preprocessing → compilation → assembly → linking
was inherited by [[C++]], [[Objective-C]], [[Rust]], and [[Wave]].

* '''Undefined Behavior Concept''' —
A philosophical legacy of C.
Some languages have eliminated it entirely (Rust, Swift),
while others retain it in restricted form (C++, D).

=== 4. Influence on Programming Culture ===
C’s impact is not limited to technology—it shaped programming culture itself.

* The “Hello, World!” program tradition
originated from the textbook ''The C Programming Language''.

* The concept that “a function is the fundamental unit of a program”
became a universal assumption in language design after C.

* C’s syntax became the shared grammar of education, research, and industry.
Today, most programmers can learn new languages quickly
because they share C-style syntax.

=== 5. Philosophical Legacy ===
C is not merely a starting point for functionality—
it became the '''philosophical benchmark''' for language design.

Its influence continues along three fundamental axes:
* '''The Power of Simplicity''' — remove unnecessary abstractions and focus on essentials.
* '''Freedom of Control''' — programmers, not the language, govern memory.
* '''The Philosophy of Efficiency''' — extract performance directly from hardware.

This enduring spirit explains why all modern languages, no matter how advanced,
are still compared and analyzed against C.

Ultimately, C is more than a programming language—
it is the '''coordinate system of programming language history'''.
All languages can be classified as either “before C” or “after C.”

== Modern Evaluation ==
Although C was designed in the early 1970s,
it remains one of the most important system programming languages in the world even in the 2020s.
Its relevance is not merely as a “historical legacy,”
but because the very foundation of modern computing still rests upon it.

=== 1. Continuing Industrial Influence ===
Most operating systems, embedded firmware, compilers, network stacks,
and database engines are either written in C or deeply interconnected with it.
Notable examples include the [[Linux]] kernel, [[Windows]] NT kernel,
the Darwin layer of [[macOS]], [[PostgreSQL]], [[MySQL]], [[Redis]], and [[Nginx]].

These systems are not ordinary applications—
they form the '''core infrastructure of modern computing''' upon which all other software depends.
Thus, C serves as the “foundational language upon which all higher-level languages operate.”

Today, most hardware APIs and OS interfaces use
the C ABI (Application Binary Interface) as a standard.
This makes C not just a language but a '''common language of systems'''.

=== 2. Technical Strengths and Reasons for Survival ===
C has endured for over half a century due to several technical advantages:

* '''Deterministic Performance''' –
With no garbage collection or runtime management,
C provides fully predictable execution time and memory usage—
essential for real-time systems, embedded devices, and kernel programming.

* '''Direct Hardware Control''' –
Through pointers and bit-level operations,
C allows direct access to memory, registers, and hardware devices—
a capability no modern high-level language can fully replace.

* '''Simple Compilation Model''' –
The consistent pipeline of preprocessing → compilation → assembly → linking
avoids complex runtimes or virtual machines,
resulting in higher portability and reliability.

* '''Transparency''' –
C code maps closely to actual machine instructions,
allowing programmers to predict memory layout and execution flow at the assembly level.

In short, C continues to dominate in three domains:
'''performance, simplicity, and control.'''

=== 3. Limitations and Criticisms ===
Despite its power, C has inherent limitations when faced with modern requirements.

* '''Lack of Memory Safety''' —
While pointer arithmetic and manual memory management offer flexibility,
they also introduce critical vulnerabilities such as buffer overflows,
invalid references (segfaults), and use-after-free errors.
Many security issues in the 2020s still originate from C code.

* '''Undefined Behavior''' —
The C standard intentionally leaves certain behaviors undefined to enable optimization,
but this leads to inconsistent results and compiler-dependent behavior.

* '''Limited Expressiveness''' —
C lacks modern abstractions such as object orientation, generics, and exception handling.
Writing large-scale systems often requires auxiliary languages or frameworks.

* '''Low Developer Productivity''' —
Manual memory management, pointer handling, and difficult debugging
make C less suitable for large-scale application development,
where speed of development and maintainability are key.

For these reasons, C is no longer a “universal language.”
Successor system languages such as [[Rust]], [[Go]], and [[Wave]]
have emerged to pursue both safety and efficiency simultaneously.

=== 4. Educational and Philosophical Value ===
Nevertheless, C remains the '''core language of computer science education'''.
This is not simply due to tradition—
C most directly reveals “how computers truly work.”

Learning C means learning memory structure, pointers, compiler mechanics,
and CPU instruction models.
Thus, universities, research institutes, and corporate training programs worldwide
continue to teach C as “the language upon which all others are built.”

From a philosophical standpoint,
C embodies the principle that “humans should master the machine, not be protected from it.”
Even as modern languages pursue automation and abstraction,
this philosophy explains why C endures.

=== 5. C’s Current Role ===
Today, C is no longer a language of rapid innovation.
Instead, it is valued for its “unchanging stability” and “established ecosystem.”
C does not aim to reinvent itself like modern languages;
most updates focus on refinement and standardization.

Since the [[C23]] standard, C continues to thrive alongside
advanced compiler infrastructures such as [[LLVM]], [[GCC]], and [[Clang]],
remaining the dominant language for kernels, networking, hardware control, and real-time systems.
Its role has shifted from “competitor among new languages”
to the enduring '''reference language for all others.'''

=== 6. Overall Evaluation ===
C remains both the foundation of modern software
and the philosophical axis of programming languages.
Its simplicity and risk are its greatest strengths,
and in terms of performance and control, it remains nearly unrivaled.

Ultimately, C is “an imperfect but fully comprehensible language,”
one that continues to define the very history of technology itself.

:''"C is both the origin and the gravity of programming languages."'' — TechPedia Editorial

== Related Articles ==
* [[Programming language]]
* [[B]]
* [[C++]]
* [[Rust]]
* [[Wave]]
* [[Assembly language]]
* [[Compiler]]
* [[Operating system]]
* [[Unix]]

== References ==
* Dennis M. Ritchie & Brian W. Kernighan, ''The C Programming Language'', Prentice Hall, 1978.
* ISO/IEC 9899:2023 – Information technology — Programming languages — C (C23 Standard).
* ISO/IEC JTC1/SC22/WG14, [https://www.open-std.org/jtc1/sc22/wg14/ Official C Language Standard Committee Website].
* Bell Labs Computer Science Research Center, ''The Development of the C Language'', Dennis Ritchie, 1993.
* Bjarne Stroustrup, ''A History of C++: 1979–1991'', ACM SIGPLAN Notices, Vol. 28, No. 3, 1993.
* GNU Project, [https://gcc.gnu.org GCC (GNU Compiler Collection) Documentation].
* Clang Project, [https://clang.llvm.org Clang: C Language Family Frontend for LLVM].

[[Category:Programming languages]]
[[Category:C family]]
[[Category:System programming]]
[[Category:1970s software]]

C

2025-10-17T07:24:13Z

LunaStev: /* Related Articles */

{{Software infobox
| Name = C
| Logo = [[File:C_logo.png|120px]]
| Developer = Dennis Ritchie
| Released = 1972
| Latest release= C17 (2018)
| Extensions = .c, .h
| License = ISO/IEC 9899
| Website = https://www.open-std.org/jtc1/sc22/wg14/
}}

== Overview ==
'''C''' is a general-purpose programming language developed by '''Dennis Ritchie''' in the early 1970s at [[Bell Labs]].
At that time, Bell Labs — led by [[Ken Thompson]] and Ritchie — was developing a new operating system called [[Unix]],
and during this process, the limitations of assembly-based systems became apparent.

In the early 1970s, every computer had its own unique instruction set,
and porting an operating system or compiler required rewriting the entire codebase.
To solve this problem, Bell Labs set a goal to create a '''“portable operating system”''',
and to achieve this, they needed a new language that preserved the low-level control of assembly
while providing the structural expressiveness of a high-level language.

It was in this context that C was born.
Ritchie improved upon [[B (programming language)]], originally developed by Thompson,
introducing a more efficient and machine-friendly design.
C was first completed in 1972, and by 1973, the entire Unix kernel was successfully rewritten in C.
This event marked a major turning point in computer science history,
establishing C as a “system-level language.”

The greatest innovation of C lies in its philosophy as a '''“machine-oriented high-level language.”'''
This concept balances performance and abstraction
by allowing direct hardware control while organizing code
into functions and logical blocks.

C was designed around the following technical principles and philosophies:
* '''Low-level accessibility''' — direct memory manipulation via pointers (<code>*</code>) and the address operator (<code>&</code>).
* '''High-level structuring''' — logical code organization using conditionals, loops, functions, and structures.
* '''Minimalism''' — exclusion of unnecessary syntax, providing flexibility through simplicity.
* '''Portability''' — independence from specific hardware, enabling recompilation on different architectures.

Furthermore, C allows explicit hardware control
while maintaining simplicity and readability suitable for human developers.
Thanks to this balance, C became a foundational language across nearly all domains —
including compilers, operating systems, embedded systems, databases, and game engines.

The structural simplicity of C influenced the design of countless later languages.
[[C++]], [[Objective-C]], [[C#]], [[Rust]], [[Go]], and [[Wave]]
inherit and extend C’s syntax, memory model, function structure, and control flow.
As a result, C is regarded not merely as a language but as
an '''architectural prototype of programming language design.'''

Even today, C continues to serve as the standard for new language and system design,
remaining indispensable in operating system development, microcontroller programming,
and modern runtime implementations.
Its philosophical essence can be summarized by the following statement:

''“C is not just a programming language; it is a way of thinking about machines.”'' — Dennis Ritchie

== History ==
The evolution of C is not merely a story of syntax changes,
but a process intertwined with the development of operating systems, compilers, and hardware architecture.
Since its birth in the early 1970s, C has undergone several rounds of standardization,
laying the foundation for modern programming language design.

=== 1970s: Birth and Establishment ===
C was developed in 1972 at [[Bell Labs]] by '''Dennis Ritchie'''.
It was influenced by [[B (programming language)]] and [[BCPL]],
and designed to efficiently implement the [[Unix]] kernel on the PDP-11 computer system.

In 1973, when the Unix kernel was largely rewritten in C,
it became the first language to enable a “machine-independent operating system implementation.”
This milestone introduced the concept of portability to the software industry.

In 1978, Ritchie and [[Brian W. Kernighan]] published
''The C Programming Language'' (commonly known as '''K&R C''').
The book became a de facto standard,
and compiler developers worldwide used it as the basis for C implementations.

=== 1980s: The Beginning of Standardization (ANSI C) ===
As C was used across different environments,
syntax discrepancies between compilers grew significantly,
creating the need for standardization.

In 1983, the '''ANSI X3J11 Committee''' was formed
to establish an official standard specification,
and in 1989, the American National Standards Institute (ANSI) approved it.

This standard, known as '''ANSI X3.159-1989''', or simply '''ANSI C''' or '''C89''',
included the following major changes:
* Clear definition of function declaration format (prototype introduction)
* Addition of standard libraries <code>stdlib.h</code>, <code>string.h</code>, <code>assert.h</code>
* Improvements to enumerations (<code>enum</code>) and constant expressions
* Establishment of a standard I/O model (<code>stdio.h</code>)

ANSI C was later adopted as an international standard by ISO in 1990,
becoming '''ISO/IEC 9899:1990''', also known as '''C90'''.

=== 1990s: The Foundation of Modern Syntax (C99) ===
After the publication of the C89/C90 standard,
C needed to adapt to rapidly advancing hardware and compiler technologies.
This led to the release of a new standard, '''C99''', in 1999.

Key changes introduced in C99 include:
* Addition of <code>//</code> single-line comments (for C++ compatibility)
* Introduction of <code>inline</code> functions for performance optimization
* Support for Variable Length Arrays (VLA)
* New integer and complex types (<code>long long</code>, <code>_Complex</code>)
* Introduction of the <code>_Bool</code> type and <code>stdbool.h</code> header
* Provision of fixed-width integer types via <code>stdint.h</code> (e.g., <code>int32_t</code>)

During this era, C was widely used across embedded systems, network devices, and scientific computing,
establishing itself as an “industrial standard language.”

=== 2010s: Parallelism and Stability (C11, C17) ===
With the rise of multicore processors, C officially embraced parallel programming.
Released in 2011, '''C11''' became the first C standard to define a formal memory model and thread safety.

Core features of C11:
* Multithreading support (<code>_Thread_local</code>, <code>atomic</code> types)
* Static assertions (<code>_Static_assert</code>)
* Support for anonymous structs and unions
* Unicode expansion (<code>uchar.h</code>)
* Safer standard functions (<code>gets()</code> removed, <code>snprintf()</code> recommended)

C11 is widely regarded as the standard that defined “modern system-level C.”

In 2018, '''C17''' (ISO/IEC 9899:2018) was released,
not as a major feature update, but as a bug-fix and cleanup revision,
serving as a stable edition of C11.

=== 2020s: Modern Refinement (C23) ===
Published in 2023, '''C23''' preserves the 50-year-old philosophy of C
while incorporating select features from modern programming languages.

Major updates include:
* Introduction of the <code>nullptr</code> keyword (as a safer alternative to <code>NULL</code>)
* Standardization of UTF-8 string literals (<code>u8""</code>)
* Addition of the <code>typeof</code> operator and type inference expressions
* Support for <code>constexpr</code>-like constant evaluation
* Formal introduction of the <code>static_assert</code> syntax
* New <code>embed</code> directive for embedding binary data

C23 is regarded as “a practical evolution that modernizes C
without transforming it into an entirely new language,”
reflecting contemporary system and compiler design principles.

From its origins as the Unix development language in the 1970s
to its continued dominance in the 2020s,
C remains the '''standard language for operating systems, compilers, embedded systems, and hardware control'''.
Even after more than 50 years, its philosophy and structure have changed little,
and C continues to be “the simplest yet most fundamental programming language.”

== Philosophy ==
The design philosophy of C is not merely a collection of syntactic rules,
but rather a '''thought paradigm''' for understanding and manipulating computer hardware.
Dennis Ritchie defined C as a “machine-oriented high-level language,”
meaning that C is more than just a programming tool —
it represents a way of thinking about computers themselves.

The philosophy of C can be summarized in four core principles.

=== 1. Minimalism ===
C was designed under the principle of “providing only what is necessary.”
The language defines only a small set of core constructs,
leaving complex functionalities to be implemented directly by the programmer.
Automated abstractions such as garbage collection, classes, and exception handling
were deliberately excluded.

This philosophy grants programmers '''absolute freedom and responsibility''',
allowing powerful systems to be built from a small language core.
This design approach was later inherited by the [[Unix]] philosophy,
forming the basis of the principle “Do one thing and do it well.”

=== 2. Machine-Oriented Abstraction ===
C aims to be a high-level language capable of directly interacting with hardware.
This embodies the idea of '''“abstraction over machine code”''',
allowing programmers to control memory addresses, pointers, and register-level operations
without writing assembly code.

This concept goes beyond hardware-friendly syntax.
C encourages programmers to “understand the machine as it truly operates.”
Thus, C serves as a linguistic interface between hardware-level control
and higher-level logical structures.

=== 3. Portability and Implementation Freedom ===
C is a compiler-centered language —
that is, its implementation (the compiler) matters more than the language definition itself.
The language provides only minimal rules,
while compilers are responsible for adapting them to different platforms.

This structure realized the concept of “write once, run anywhere.”
One of C’s core ideas is that “a language should not be bound to a specific machine,”
which was the fundamental reason [[Unix]] could be ported across diverse hardware.

At the same time, C deliberately allows '''undefined behavior''',
maximizing compiler optimization and implementation freedom.
Although rare in modern languages,
this approach was key to preserving C’s performance and simplicity.

=== 4. Freedom and Responsibility ===
C gives nearly all control to the programmer.
Memory management, type casting, pointer arithmetic, and bit operations
are all left in the user’s hands.
Safety mechanisms are minimal,
and incorrect operations can immediately lead to crashes or undefined results.

This design reflects the philosophy of prioritizing “control over safety.”
C does not protect the programmer —
instead, it offers the same level of freedom as the machine itself.
This attitude solidified C’s identity as a “language equal to the machine.”

=== 5. Simplicity and Extensibility ===
C is simple, yet capable of expressing all forms of complexity.
Though the language is small, its composability allows developers to build
operating systems, compilers, graphics engines, and virtual machines.

This is why C is often described as “a small language, but a complete one.”
As Ritchie once said:
:''"C was not designed to hide the machine, but to express it efficiently."''

In other words, C’s simplicity is not a limitation of expression,
but a deliberate choice to maximize expressive efficiency.

=== 6. Philosophical Influence on Modern Languages ===
C’s philosophy became the foundational principle for many later languages:
* [[C++]] — added object-orientation and encapsulation atop C’s structure.
* [[Rust]] — inherited C’s performance and low-level control while reinforcing safety.
* [[Go]] — applied C’s simplicity and explicit control to modern system programming.
* [[Wave]] — reimagined and modernized C’s memory model and philosophy as a next-generation low-level language.

Thus, C has transcended its role as a language,
becoming the '''philosophical origin of programming languages'''.
Its core ideals — minimalism, portability, control, and simplicity —
remain the foundation of all modern system programming languages to this day.

== Key Features ==
C combines structural simplicity with low-level hardware control,
achieving both high performance and flexibility through the following technical features.

=== 1. Static Type System ===
In C, every variable’s data type must be explicitly declared at '''compile time'''.
This ensures predictable program behavior and allows the compiler
to determine memory size and operation methods in advance.

For example, operations between <code>int</code> and <code>float</code> are strictly distinguished at compile time,
executing without runtime overhead.
This '''statically analyzed design''' contrasts with modern dynamic languages,
enabling C to closely correspond to hardware operations.

C also supports both '''implicit casting''' and '''explicit casting''',
granting programmers full control over type conversions.
While powerful, these conversions may cause '''precision loss''' or '''overflow errors''' if misused.

=== 2. Pointers and Direct Memory Access ===
One of C’s most distinctive features is the concept of pointers.
A pointer holds a memory address as its value,
allowing direct reading and writing to memory regions.

<syntaxhighlight lang="c">
int a = 10;
int *p = &a;
printf("%d\n", *p); // prints 10
</syntaxhighlight>

Pointers are both the source of C’s power and its danger.
They enable indirect access to arrays, functions, and structures,
making them indispensable in low-level development such as kernels and drivers.

However, incorrect address access can cause a '''Segmentation Fault''',
which is why C is often described as an “unsafe but predictable” language.

=== 3. Manual Memory Management ===
C does not include garbage collection (GC).
Memory allocation and deallocation are entirely the programmer’s responsibility.

<syntaxhighlight lang="c">
int *arr = malloc(sizeof(int) * 5);
...
free(arr);
</syntaxhighlight>

Functions like <code>malloc()</code>, <code>calloc()</code>, <code>realloc()</code>, and <code>free()</code>
are defined in the standard library <code>stdlib.h</code>.
This manual management model offers '''maximum performance''',
but improper use can lead to '''memory leaks''' or '''double-free errors'''.

Unlike modern languages with automatic memory management,
C’s model reflects its philosophy of total system resource control.

=== 4. Preprocessor ===
Before actual compilation, the C compiler performs a '''preprocessing''' phase.
This processes directives beginning with the <code>#</code> symbol,
providing significant structural flexibility to the language.

Common preprocessor directives include:
* <code>#include</code> – include external header files
* <code>#define</code> – define macros
* <code>#ifdef</code>, <code>#ifndef</code>, <code>#endif</code> – conditional compilation

Although technically just text substitution,
the preprocessor provides flexibility for C’s build system
and is essential for managing platform-specific code in large projects.

=== 5. Structured Programming ===
C is a procedural language that adopts block structures to implement '''structured programming'''.
It organizes control flow into functions
and provides explicit structures using <code>if</code> statements, loops (<code>for</code>, <code>while</code>),
and the <code>switch</code> statement.

<syntaxhighlight lang="c">
for (int i = 0; i < 5; i++) {
printf("%d\n", i);
}
</syntaxhighlight>

This design improved readability and maintainability,
breaking away from the linear control flow of [[B language]] and [[assembly language]],
and establishing the concept of “logical program composition.”

Later languages such as [[Pascal]], [[C++]], and [[Rust]] inherited this paradigm.

=== 6. Function-Centric Architecture ===
C follows the rule that “all code executes within a function.”
Every executable program must have a <code>main()</code> function,
and all functions must declare explicit return types and parameter lists.

<syntaxhighlight lang="c">
int add(int a, int b) {
return a + b;
}
</syntaxhighlight>

Since C89, the function '''prototype''' format was introduced,
allowing compilers to check argument types and improve type safety at call time.

C’s function architecture influenced later developments such as
[[C++]] methods, [[Rust]]’s functional model, and [[Wave]]’s chain APIs.

=== 7. Platform Independence ===
C was designed with the principle of “not being tied to any machine.”
Instead of using assembly code specific to a CPU or OS,
it enables hardware-independent source code that compilers translate appropriately.

Portability is one of C’s defining features,
allowing the same code to be recompiled and run on Windows, Linux, macOS, Unix, and more.

This is made possible by features like <code>sizeof</code>, <code>typedef</code>,
and the <code>std*</code> family of types, which abstract differences in memory size across platforms.

=== 8. Standard Library ===
The C Standard Library is a core component that extends the language’s functionality.
It includes file I/O, string manipulation, mathematical operations, and memory management,
enabling basic system-level tasks without OS-specific calls.

Key header files include:
* <code>stdio.h</code> – standard input/output
* <code>stdlib.h</code> – memory management and utilities
* <code>string.h</code> – string operations
* <code>math.h</code> – mathematical functions
* <code>time.h</code> – time-related utilities

The standard library is defined by the ISO standard,
and all C implementations are required to support it.

=== 9. Combination of Efficiency and Simplicity ===
C merges near-hardware efficiency with a readable high-level syntax.
As a result, C programs are both fast and lightweight while remaining human-readable.

This balance is one of the main reasons C has endured for over half a century,
remaining the standard for operating systems, compilers, embedded systems,
and all environments where “performance is everything.”

=== 10. Undefined Behavior ===
C explicitly allows certain undefined behaviors,
leaving room for compiler optimization.

Examples include pointer access beyond memory bounds
or using uninitialized variables — both considered “undefined behavior.”
This flexibility grants compiler implementers freedom,
but introduces potential risks to program stability.

It is both the reason for C’s remarkable performance
and the reason it demands a high level of responsibility from its programmers.

== Basic Structure ==
C programs follow the structural principle that “all code executes within functions.”
The most important entry point is the <code>main()</code> function,
where the program’s execution begins and ends.

C has a modular architecture.
Each source file (<code>.c</code>) contains one or more functions,
and header files (<code>.h</code>) are used to share declarations and interfaces between modules.

Every C program consists of three main components:
# '''Preprocessing section''' – directives such as <code>#include</code> and <code>#define</code>.
# '''Function section''' – <code>main()</code> and user-defined functions.
# '''Data section''' – global variables, constants, and structure definitions.

The following is the simplest example of a C program structure:

<syntaxhighlight lang="c">
#include <stdio.h>

int main(void) {
printf("Hello, World!\n");
return 0;
}
</syntaxhighlight>

The <code>#include</code> directive instructs the preprocessor to include the standard library,
and the <code>main()</code> function serves as the program’s entry point.
The C compiler always looks for and begins execution from <code>main()</code>.
This structure was later inherited by [[C++]], [[Rust]], and [[Wave]].

The structural simplicity of C became a standard paradigm
for compiler design, operating system development, and embedded systems programming.

=== Data Types ===
C’s data types are directly linked to the hardware memory model.
Each data type explicitly defines its '''storage size''', '''signness''', and permissible operations,
which determine both performance and memory efficiency.

The basic data types are as follows:

{| class="wikitable"
! Category !! Type !! Typical Size !! Description
|-
| Integer || <code>char</code> || 1 byte || Character or 8-bit integer
|-
| Integer || <code>short</code> || 2 bytes || Small integer
|-
| Integer || <code>int</code> || 4 bytes || Standard integer type
|-
| Integer || <code>long</code> || 4–8 bytes || Large integer
|-
| Floating-point || <code>float</code> || 4 bytes || Single-precision float
|-
| Floating-point || <code>double</code> || 8 bytes || Double-precision float
|-
| Boolean || <code>_Bool</code> || 1 byte || Introduced in C99
|}

Starting with the C99 standard,
<code>stdint.h</code> introduced fixed-width integer types such as
<code>int8_t</code>, <code>int32_t</code>, and <code>uint64_t</code>,
ensuring consistency across platforms.

C also supports composite data types:
* <code>struct</code> – groups multiple variables into a single logical unit.
* <code>union</code> – allows different types to share the same memory space.
* <code>enum</code> – defines a set of named constants.
* <code>typedef</code> – assigns aliases to existing types.

Although simple, C’s type system enables highly efficient code generation
that maps closely to hardware architecture.

=== Control Statements ===
C’s control statements define the logical flow of program execution.
Conditionals and loops are high-level abstractions of assembly-level branch instructions,
forming the foundation of all imperative programming logic.

* Conditionals: <code>if</code>, <code>else if</code>, <code>else</code>
* Selection: <code>switch</code> / <code>case</code>
* Loops: <code>for</code>, <code>while</code>, <code>do-while</code>
* Flow control: <code>break</code>, <code>continue</code>, <code>goto</code>

Example:

<syntaxhighlight lang="c">
for (int i = 0; i < 5; i++) {
if (i == 3) continue;
printf("%d\n", i);
}
</syntaxhighlight>

C’s control statements not only branch logic flow,
but also define the conceptual structure of imperative programming.
Because these statements map directly to machine instructions,
they enable compilers to perform efficient low-level optimizations.

=== Memory and Pointers ===
At the heart of C lies the ability to “manipulate memory addresses.”
This capability is what makes C not just a high-level language,
but a true '''system language'''.

A pointer is a variable that stores a memory address,
allowing indirect access or modification of another variable’s value.

<syntaxhighlight lang="c">
int x = 42;
int *ptr = &x;
printf("%d\n", *ptr);
</syntaxhighlight>

Here, <code>&</code> is the address-of operator,
and <code>*</code> is the dereference operator.
Thus, <code>*ptr</code> reads the actual memory value of <code>x</code>.

Through pointer operations, C allows low-level control such as:
* Direct memory access and modification
* Efficient array and string handling
* Function pointers for callback implementations
* Dynamic memory allocation (<code>malloc()</code>, <code>free()</code>)

This structure made C the optimal language for developing
operating systems, drivers, and firmware — domains that require direct hardware control.
However, incorrect memory access can cause immediate program crashes,
a risk considered part of C’s core philosophy:
“with freedom comes responsibility.”

=== Compilation Process ===
C is a '''compiled language''', meaning source code must be translated
into machine code before execution.
The compilation process consists of four main stages:

# '''Preprocessing'''
Handles directives such as <code>#include</code> and <code>#define</code>,
performing conditional compilation and macro expansion.
# '''Compilation'''
Translates preprocessed code into assembly code,
performing syntax analysis, type checking, and optimization.
# '''Assembly'''
Converts assembly code into object files (<code>.o</code>).
# '''Linking'''
Combines multiple object files and libraries
into the final executable (<code>.exe</code> or ELF binary).

Example of a typical build process on Linux:

<syntaxhighlight lang="bash">
gcc -E main.c -o main.i # Preprocessing
gcc -S main.i -o main.s # Compilation
gcc -c main.s -o main.o # Assembly
gcc main.o -o main # Linking
</syntaxhighlight>

This multi-stage structure not only reflects C’s simplicity
but also served as the foundation model for [[compiler]] design.
Most modern compilers are built upon this architecture.

Throughout the entire process, C maintains its essence
as a language that expresses programs directly at the hardware level.
As a result, C enables efficient use of system resources
while allowing developers to write readable and structured code —
earning its reputation as a “machine-friendly high-level language.”

== Standard Macros ==
The C standard defines a set of '''predefined macros''' that every implementation (compiler) must provide.
These macros convey information about the compiler environment, standard version, and platform,
helping programs behave correctly across different systems.

Standard macros are recognized during the '''preprocessing stage''',
and are determined at '''compile time''', not at runtime.
In essence, the preprocessor in C functions as a “compiler–language interface” for environment metadata.

=== Major Macro List ===
The following table summarizes the representative macros defined by the ISO/IEC C standard and their purposes.

{| class="wikitable"
! Macro Name !! Description !! Introduced In
|-
| <code>__STDC__</code> ||
Indicates that the compiler conforms to the ANSI/ISO C standard.
A value of 1 signifies a standard-compliant implementation. || C89
|-
| <code>__STDC_VERSION__</code> ||
Specifies the supported version of the C standard.
Examples:
<code>199409L</code> → C94
<code>199901L</code> → C99
<code>201112L</code> → C11
<code>201710L</code> → C17
<code>202311L</code> → C23 || C90 and later
|-
| <code>__STDC_HOSTED__</code> ||
Indicates whether the environment is hosted (with standard library support)
or freestanding (independent, e.g., kernel or embedded).
1 = hosted, 0 = freestanding. || C99
|-
| <code>__FILE__</code> ||
String literal of the current source filename being compiled. || C89
|-
| <code>__LINE__</code> ||
Current line number in the source file. Useful for debugging and logging. || C89
|-
| <code>__DATE__</code> ||
Compilation date as a string (e.g., "Oct 17 2025"). || C89
|-
| <code>__TIME__</code> ||
Compilation time as a string (e.g., "14:30:42"). || C89
|-
| <code>__func__</code> ||
Returns the current function name as a string.
<syntaxhighlight lang="c">
void test() {
printf("%s\n", __func__);
}
</syntaxhighlight>
The above code prints "test". || C99
|-
| <code>__STDC_NO_ATOMICS__</code> ||
Defined as 1 if the compiler does not support <code>_Atomic</code>. || C11
|-
| <code>__STDC_NO_THREADS__</code> ||
Defined if the compiler does not support the standard threads library (<code>threads.h</code>). || C11
|-
| <code>__STDC_UTF_16__</code>, <code>__STDC_UTF_32__</code> ||
Indicates support for UTF-16 and UTF-32 character types. || C11
|-
| <code>__STDC_ANALYZABLE__</code> ||
Indicates whether static analysis features are supported. || C23
|-
| <code>__STDC_VERSION_STDINT_H__</code> ||
Specifies the version of <code>stdint.h</code>,
confirming support for standard integer types. || C23
|}

In addition to these, many compilers (e.g., GCC, Clang, MSVC)
provide their own proprietary extension macros.
For example, GCC defines <code>__GNUC__</code>, and MSVC defines <code>_MSC_VER</code>.

=== Role and Significance of Macros ===
Standard macros are not mere constants —
they serve as a '''linguistic interface between the compiler and the program'''.
By providing “compile-time environment information” rather than runtime data,
they allow conditional compilation and environment-specific behavior.

For instance, the following code performs compiler-specific conditional builds:

<syntaxhighlight lang="c">
#ifdef __GNUC__
printf("Compiled with GCC\n");
#elif defined(_MSC_VER)
printf("Compiled with MSVC\n");
#else
printf("Unknown compiler\n");
#endif
</syntaxhighlight>

This mechanism is one of the key reasons C achieves portability and implementation independence.
The source code remains identical,
but compilers can generate machine code tailored to their environments
by '''exposing system information through preprocessor macros'''.

=== Philosophical Aspect ===
C’s standard macro system is not merely an extension of preprocessing capabilities —
it embodies the language’s core philosophy:
'''“The language should be small, and the implementation should be powerful.”'''
The language defines only minimal promises,
delegating environmental awareness to the compiler through the preprocessor.

This design directly influenced the build systems and compiler metadata handling
in later languages such as [[C++]], [[Rust]], and [[Wave]].
In particular, the <code>build.meta</code> system in the Wave language
is considered an evolved form of C’s preprocessor macro concept.

Ultimately, standard macros serve as an intermediary layer
linking the language, compiler, and hardware —
the very mechanism that has allowed C to maintain its '''portability and implementation freedom'''
for over half a century.

== Influence on Other Languages ==
C became the foundation of nearly all major programming languages developed since the late 20th century.
Its influence extends far beyond syntax—encompassing philosophy, memory models, compiler design, and error-handling paradigms.
In other words, C did not merely shape “the form of languages” but “the way languages think.”

=== 1. Direct Descendant Languages ===
Languages that directly inherited C’s structure and syntax are collectively called the “C family.”
They evolved from C’s syntax, expression structure, and the concepts of pointers or references.

* '''C++''' — developed by [[Bjarne Stroustrup]] in 1983.
It extended C by adding classes, objects, inheritance, templates, and other
'''object-oriented''' features.
Maintaining backward compatibility with C,
C++ achieved both hardware-level control and high-level abstraction—
earning the title “the language that expanded C’s philosophy.”

* '''Objective-C''' — created in the 1980s by [[Brad Cox]] and [[Tom Love]].
It combined C syntax with Smalltalk’s message-passing paradigm.
It became the foundation for [[NeXTSTEP]], [[macOS]], and [[iOS]],
defining Apple’s entire software ecosystem.

* '''C#''' — designed by [[Anders Hejlsberg]] at [[Microsoft]].
Built on C/C++ syntax, it was made to operate within the .NET Framework.
It preserved C’s syntactic familiarity while introducing garbage collection and runtime safety.

* '''Java''' — simplified C++’s syntax and abstracted its memory model.
Although it runs entirely within a virtual machine,
its control structures, operators, and type system remain largely C-like.

All of these languages share the common goal of being “C-like but safer than C.”

=== 2. Indirect Influence (Structure and Philosophy) ===
C’s influence extends into language design philosophies as well.

* '''Rust''' — inherited C’s low-level control philosophy,
but introduced ownership and compile-time validation
to ensure memory safety.
It is often described as “C without undefined behavior.”

* '''Go''' — retained C’s simplicity and explicit control structures
while modernizing the model for concurrency and network programming.
Since [[Ken Thompson]] and [[Rob Pike]]—key C developers—were involved,
Go is regarded as a spiritual successor to C.

* '''D language''' — maintained the performance of C and C++
while integrating modern abstractions and managed memory.
Strong interoperability with C code is one of its core traits.

* '''Swift''' — Apple’s successor to Objective-C,
replacing the C-based runtime with a modern type system.
Yet, its ABI and runtime architecture remain deeply influenced by C.

* '''Wave''' — a next-generation system language
that fundamentally inherits C’s memory model and compiler philosophy,
removing unnecessary complexity while experimenting with new syntax structures.
It preserves C’s core concept of “machine-oriented abstraction.”

=== 3. Conceptual Influence Inside Languages ===
C’s legacy also extends deep into the internal structure of modern languages.

* '''Operator Semantics''' —
Most languages directly reuse C’s operator system.
Examples include <code>++</code>, <code>--</code>, <code>==</code>, <code>!=</code>, and <code>+=</code>.
This syntax has effectively become the “industry standard operator notation.”

* '''Standard Library Architecture''' —
The structure of C’s headers—<code>stdio</code>, <code>stdlib</code>, and <code>string</code>—
laid the groundwork for modern module and package systems.

* '''Compilation Model''' —
The pipeline of preprocessing → compilation → assembly → linking
was inherited by [[C++]], [[Objective-C]], [[Rust]], and [[Wave]].

* '''Undefined Behavior Concept''' —
A philosophical legacy of C.
Some languages have eliminated it entirely (Rust, Swift),
while others retain it in restricted form (C++, D).

=== 4. Influence on Programming Culture ===
C’s impact is not limited to technology—it shaped programming culture itself.

* The “Hello, World!” program tradition
originated from the textbook ''The C Programming Language''.

* The concept that “a function is the fundamental unit of a program”
became a universal assumption in language design after C.

* C’s syntax became the shared grammar of education, research, and industry.
Today, most programmers can learn new languages quickly
because they share C-style syntax.

=== 5. Philosophical Legacy ===
C is not merely a starting point for functionality—
it became the '''philosophical benchmark''' for language design.

Its influence continues along three fundamental axes:
* '''The Power of Simplicity''' — remove unnecessary abstractions and focus on essentials.
* '''Freedom of Control''' — programmers, not the language, govern memory.
* '''The Philosophy of Efficiency''' — extract performance directly from hardware.

This enduring spirit explains why all modern languages, no matter how advanced,
are still compared and analyzed against C.

Ultimately, C is more than a programming language—
it is the '''coordinate system of programming language history'''.
All languages can be classified as either “before C” or “after C.”

== Modern Evaluation ==
Although C was designed in the early 1970s,
it remains one of the most important system programming languages in the world even in the 2020s.
Its relevance is not merely as a “historical legacy,”
but because the very foundation of modern computing still rests upon it.

=== 1. Continuing Industrial Influence ===
Most operating systems, embedded firmware, compilers, network stacks,
and database engines are either written in C or deeply interconnected with it.
Notable examples include the [[Linux]] kernel, [[Windows]] NT kernel,
the Darwin layer of [[macOS]], [[PostgreSQL]], [[MySQL]], [[Redis]], and [[Nginx]].

These systems are not ordinary applications—
they form the '''core infrastructure of modern computing''' upon which all other software depends.
Thus, C serves as the “foundational language upon which all higher-level languages operate.”

Today, most hardware APIs and OS interfaces use
the C ABI (Application Binary Interface) as a standard.
This makes C not just a language but a '''common language of systems'''.

=== 2. Technical Strengths and Reasons for Survival ===
C has endured for over half a century due to several technical advantages:

* '''Deterministic Performance''' –
With no garbage collection or runtime management,
C provides fully predictable execution time and memory usage—
essential for real-time systems, embedded devices, and kernel programming.

* '''Direct Hardware Control''' –
Through pointers and bit-level operations,
C allows direct access to memory, registers, and hardware devices—
a capability no modern high-level language can fully replace.

* '''Simple Compilation Model''' –
The consistent pipeline of preprocessing → compilation → assembly → linking
avoids complex runtimes or virtual machines,
resulting in higher portability and reliability.

* '''Transparency''' –
C code maps closely to actual machine instructions,
allowing programmers to predict memory layout and execution flow at the assembly level.

In short, C continues to dominate in three domains:
'''performance, simplicity, and control.'''

=== 3. Limitations and Criticisms ===
Despite its power, C has inherent limitations when faced with modern requirements.

* '''Lack of Memory Safety''' —
While pointer arithmetic and manual memory management offer flexibility,
they also introduce critical vulnerabilities such as buffer overflows,
invalid references (segfaults), and use-after-free errors.
Many security issues in the 2020s still originate from C code.

* '''Undefined Behavior''' —
The C standard intentionally leaves certain behaviors undefined to enable optimization,
but this leads to inconsistent results and compiler-dependent behavior.

* '''Limited Expressiveness''' —
C lacks modern abstractions such as object orientation, generics, and exception handling.
Writing large-scale systems often requires auxiliary languages or frameworks.

* '''Low Developer Productivity''' —
Manual memory management, pointer handling, and difficult debugging
make C less suitable for large-scale application development,
where speed of development and maintainability are key.

For these reasons, C is no longer a “universal language.”
Successor system languages such as [[Rust]], [[Go]], and [[Wave]]
have emerged to pursue both safety and efficiency simultaneously.

=== 4. Educational and Philosophical Value ===
Nevertheless, C remains the '''core language of computer science education'''.
This is not simply due to tradition—
C most directly reveals “how computers truly work.”

Learning C means learning memory structure, pointers, compiler mechanics,
and CPU instruction models.
Thus, universities, research institutes, and corporate training programs worldwide
continue to teach C as “the language upon which all others are built.”

From a philosophical standpoint,
C embodies the principle that “humans should master the machine, not be protected from it.”
Even as modern languages pursue automation and abstraction,
this philosophy explains why C endures.

=== 5. C’s Current Role ===
Today, C is no longer a language of rapid innovation.
Instead, it is valued for its “unchanging stability” and “established ecosystem.”
C does not aim to reinvent itself like modern languages;
most updates focus on refinement and standardization.

Since the [[C23]] standard, C continues to thrive alongside
advanced compiler infrastructures such as [[LLVM]], [[GCC]], and [[Clang]],
remaining the dominant language for kernels, networking, hardware control, and real-time systems.
Its role has shifted from “competitor among new languages”
to the enduring '''reference language for all others.'''

=== 6. Overall Evaluation ===
C remains both the foundation of modern software
and the philosophical axis of programming languages.
Its simplicity and risk are its greatest strengths,
and in terms of performance and control, it remains nearly unrivaled.

Ultimately, C is “an imperfect but fully comprehensible language,”
one that continues to define the very history of technology itself.

:''"C is both the origin and the gravity of programming languages."'' — TechPedia Editorial

== Related Articles ==
* [[Programming language]]
* [[B]]
* [[C++]]
* [[Rust]]
* [[Wave]]
* [[Assembly language]]
* [[Compiler]]
* [[Operating system]]
* [[Unix]]

== References ==
* Dennis M. Ritchie & Brian W. Kernighan, ''The C Programming Language'', Prentice Hall, 1978.
* ISO/IEC 9899:2023 – Information technology — Programming languages — C (C23 Standard).
* ISO/IEC JTC1/SC22/WG14, [https://www.open-std.org/jtc1/sc22/wg14/ Official C Language Standard Committee Website].
* Bell Labs Computer Science Research Center, ''The Development of the C Language'', Dennis Ritchie, 1993.
* Bjarne Stroustrup, ''A History of C++: 1979–1991'', ACM SIGPLAN Notices, Vol. 28, No. 3, 1993.
* GNU Project, [https://gcc.gnu.org GCC (GNU Compiler Collection) Documentation].
* Clang Project, [https://clang.llvm.org Clang: C Language Family Frontend for LLVM].

[[Category:Programming languages]]
[[Category:C family]]
[[Category:System programming]]
[[Category:1970s software]]

File:C logo.png

2025-10-17T07:08:22Z

LunaStev:

C

2025-10-17T07:07:17Z

LunaStev:

{{Software infobox
| Name = C
| Logo = [[File:C_logo.png|120px]]
| Developer = Dennis Ritchie
| Released = 1972
| Latest release= C17 (2018)
| Extensions = .c, .h
| License = ISO/IEC 9899
| Website = https://www.open-std.org/jtc1/sc22/wg14/
}}

== Overview ==
'''C''' is a general-purpose programming language developed by '''Dennis Ritchie''' in the early 1970s at [[Bell Labs]].
At that time, Bell Labs — led by [[Ken Thompson]] and Ritchie — was developing a new operating system called [[Unix]],
and during this process, the limitations of assembly-based systems became apparent.

In the early 1970s, every computer had its own unique instruction set,
and porting an operating system or compiler required rewriting the entire codebase.
To solve this problem, Bell Labs set a goal to create a '''“portable operating system”''',
and to achieve this, they needed a new language that preserved the low-level control of assembly
while providing the structural expressiveness of a high-level language.

It was in this context that C was born.
Ritchie improved upon [[B (programming language)]], originally developed by Thompson,
introducing a more efficient and machine-friendly design.
C was first completed in 1972, and by 1973, the entire Unix kernel was successfully rewritten in C.
This event marked a major turning point in computer science history,
establishing C as a “system-level language.”

The greatest innovation of C lies in its philosophy as a '''“machine-oriented high-level language.”'''
This concept balances performance and abstraction
by allowing direct hardware control while organizing code
into functions and logical blocks.

C was designed around the following technical principles and philosophies:
* '''Low-level accessibility''' — direct memory manipulation via pointers (<code>*</code>) and the address operator (<code>&</code>).
* '''High-level structuring''' — logical code organization using conditionals, loops, functions, and structures.
* '''Minimalism''' — exclusion of unnecessary syntax, providing flexibility through simplicity.
* '''Portability''' — independence from specific hardware, enabling recompilation on different architectures.

Furthermore, C allows explicit hardware control
while maintaining simplicity and readability suitable for human developers.
Thanks to this balance, C became a foundational language across nearly all domains —
including compilers, operating systems, embedded systems, databases, and game engines.

The structural simplicity of C influenced the design of countless later languages.
[[C++]], [[Objective-C]], [[C#]], [[Rust]], [[Go]], and [[Wave]]
inherit and extend C’s syntax, memory model, function structure, and control flow.
As a result, C is regarded not merely as a language but as
an '''architectural prototype of programming language design.'''

Even today, C continues to serve as the standard for new language and system design,
remaining indispensable in operating system development, microcontroller programming,
and modern runtime implementations.
Its philosophical essence can be summarized by the following statement:

''“C is not just a programming language; it is a way of thinking about machines.”'' — Dennis Ritchie

== History ==
The evolution of C is not merely a story of syntax changes,
but a process intertwined with the development of operating systems, compilers, and hardware architecture.
Since its birth in the early 1970s, C has undergone several rounds of standardization,
laying the foundation for modern programming language design.

=== 1970s: Birth and Establishment ===
C was developed in 1972 at [[Bell Labs]] by '''Dennis Ritchie'''.
It was influenced by [[B (programming language)]] and [[BCPL]],
and designed to efficiently implement the [[Unix]] kernel on the PDP-11 computer system.

In 1973, when the Unix kernel was largely rewritten in C,
it became the first language to enable a “machine-independent operating system implementation.”
This milestone introduced the concept of portability to the software industry.

In 1978, Ritchie and [[Brian W. Kernighan]] published
''The C Programming Language'' (commonly known as '''K&R C''').
The book became a de facto standard,
and compiler developers worldwide used it as the basis for C implementations.

=== 1980s: The Beginning of Standardization (ANSI C) ===
As C was used across different environments,
syntax discrepancies between compilers grew significantly,
creating the need for standardization.

In 1983, the '''ANSI X3J11 Committee''' was formed
to establish an official standard specification,
and in 1989, the American National Standards Institute (ANSI) approved it.

This standard, known as '''ANSI X3.159-1989''', or simply '''ANSI C''' or '''C89''',
included the following major changes:
* Clear definition of function declaration format (prototype introduction)
* Addition of standard libraries <code>stdlib.h</code>, <code>string.h</code>, <code>assert.h</code>
* Improvements to enumerations (<code>enum</code>) and constant expressions
* Establishment of a standard I/O model (<code>stdio.h</code>)

ANSI C was later adopted as an international standard by ISO in 1990,
becoming '''ISO/IEC 9899:1990''', also known as '''C90'''.

=== 1990s: The Foundation of Modern Syntax (C99) ===
After the publication of the C89/C90 standard,
C needed to adapt to rapidly advancing hardware and compiler technologies.
This led to the release of a new standard, '''C99''', in 1999.

Key changes introduced in C99 include:
* Addition of <code>//</code> single-line comments (for C++ compatibility)
* Introduction of <code>inline</code> functions for performance optimization
* Support for Variable Length Arrays (VLA)
* New integer and complex types (<code>long long</code>, <code>_Complex</code>)
* Introduction of the <code>_Bool</code> type and <code>stdbool.h</code> header
* Provision of fixed-width integer types via <code>stdint.h</code> (e.g., <code>int32_t</code>)

During this era, C was widely used across embedded systems, network devices, and scientific computing,
establishing itself as an “industrial standard language.”

=== 2010s: Parallelism and Stability (C11, C17) ===
With the rise of multicore processors, C officially embraced parallel programming.
Released in 2011, '''C11''' became the first C standard to define a formal memory model and thread safety.

Core features of C11:
* Multithreading support (<code>_Thread_local</code>, <code>atomic</code> types)
* Static assertions (<code>_Static_assert</code>)
* Support for anonymous structs and unions
* Unicode expansion (<code>uchar.h</code>)
* Safer standard functions (<code>gets()</code> removed, <code>snprintf()</code> recommended)

C11 is widely regarded as the standard that defined “modern system-level C.”

In 2018, '''C17''' (ISO/IEC 9899:2018) was released,
not as a major feature update, but as a bug-fix and cleanup revision,
serving as a stable edition of C11.

=== 2020s: Modern Refinement (C23) ===
Published in 2023, '''C23''' preserves the 50-year-old philosophy of C
while incorporating select features from modern programming languages.

Major updates include:
* Introduction of the <code>nullptr</code> keyword (as a safer alternative to <code>NULL</code>)
* Standardization of UTF-8 string literals (<code>u8""</code>)
* Addition of the <code>typeof</code> operator and type inference expressions
* Support for <code>constexpr</code>-like constant evaluation
* Formal introduction of the <code>static_assert</code> syntax
* New <code>embed</code> directive for embedding binary data

C23 is regarded as “a practical evolution that modernizes C
without transforming it into an entirely new language,”
reflecting contemporary system and compiler design principles.

From its origins as the Unix development language in the 1970s
to its continued dominance in the 2020s,
C remains the '''standard language for operating systems, compilers, embedded systems, and hardware control'''.
Even after more than 50 years, its philosophy and structure have changed little,
and C continues to be “the simplest yet most fundamental programming language.”

== Philosophy ==
The design philosophy of C is not merely a collection of syntactic rules,
but rather a '''thought paradigm''' for understanding and manipulating computer hardware.
Dennis Ritchie defined C as a “machine-oriented high-level language,”
meaning that C is more than just a programming tool —
it represents a way of thinking about computers themselves.

The philosophy of C can be summarized in four core principles.

=== 1. Minimalism ===
C was designed under the principle of “providing only what is necessary.”
The language defines only a small set of core constructs,
leaving complex functionalities to be implemented directly by the programmer.
Automated abstractions such as garbage collection, classes, and exception handling
were deliberately excluded.

This philosophy grants programmers '''absolute freedom and responsibility''',
allowing powerful systems to be built from a small language core.
This design approach was later inherited by the [[Unix]] philosophy,
forming the basis of the principle “Do one thing and do it well.”

=== 2. Machine-Oriented Abstraction ===
C aims to be a high-level language capable of directly interacting with hardware.
This embodies the idea of '''“abstraction over machine code”''',
allowing programmers to control memory addresses, pointers, and register-level operations
without writing assembly code.

This concept goes beyond hardware-friendly syntax.
C encourages programmers to “understand the machine as it truly operates.”
Thus, C serves as a linguistic interface between hardware-level control
and higher-level logical structures.

=== 3. Portability and Implementation Freedom ===
C is a compiler-centered language —
that is, its implementation (the compiler) matters more than the language definition itself.
The language provides only minimal rules,
while compilers are responsible for adapting them to different platforms.

This structure realized the concept of “write once, run anywhere.”
One of C’s core ideas is that “a language should not be bound to a specific machine,”
which was the fundamental reason [[Unix]] could be ported across diverse hardware.

At the same time, C deliberately allows '''undefined behavior''',
maximizing compiler optimization and implementation freedom.
Although rare in modern languages,
this approach was key to preserving C’s performance and simplicity.

=== 4. Freedom and Responsibility ===
C gives nearly all control to the programmer.
Memory management, type casting, pointer arithmetic, and bit operations
are all left in the user’s hands.
Safety mechanisms are minimal,
and incorrect operations can immediately lead to crashes or undefined results.

This design reflects the philosophy of prioritizing “control over safety.”
C does not protect the programmer —
instead, it offers the same level of freedom as the machine itself.
This attitude solidified C’s identity as a “language equal to the machine.”

=== 5. Simplicity and Extensibility ===
C is simple, yet capable of expressing all forms of complexity.
Though the language is small, its composability allows developers to build
operating systems, compilers, graphics engines, and virtual machines.

This is why C is often described as “a small language, but a complete one.”
As Ritchie once said:
:''"C was not designed to hide the machine, but to express it efficiently."''

In other words, C’s simplicity is not a limitation of expression,
but a deliberate choice to maximize expressive efficiency.

=== 6. Philosophical Influence on Modern Languages ===
C’s philosophy became the foundational principle for many later languages:
* [[C++]] — added object-orientation and encapsulation atop C’s structure.
* [[Rust]] — inherited C’s performance and low-level control while reinforcing safety.
* [[Go]] — applied C’s simplicity and explicit control to modern system programming.
* [[Wave]] — reimagined and modernized C’s memory model and philosophy as a next-generation low-level language.

Thus, C has transcended its role as a language,
becoming the '''philosophical origin of programming languages'''.
Its core ideals — minimalism, portability, control, and simplicity —
remain the foundation of all modern system programming languages to this day.

== Key Features ==
C combines structural simplicity with low-level hardware control,
achieving both high performance and flexibility through the following technical features.

=== 1. Static Type System ===
In C, every variable’s data type must be explicitly declared at '''compile time'''.
This ensures predictable program behavior and allows the compiler
to determine memory size and operation methods in advance.

For example, operations between <code>int</code> and <code>float</code> are strictly distinguished at compile time,
executing without runtime overhead.
This '''statically analyzed design''' contrasts with modern dynamic languages,
enabling C to closely correspond to hardware operations.

C also supports both '''implicit casting''' and '''explicit casting''',
granting programmers full control over type conversions.
While powerful, these conversions may cause '''precision loss''' or '''overflow errors''' if misused.

=== 2. Pointers and Direct Memory Access ===
One of C’s most distinctive features is the concept of pointers.
A pointer holds a memory address as its value,
allowing direct reading and writing to memory regions.

<syntaxhighlight lang="c">
int a = 10;
int *p = &a;
printf("%d\n", *p); // prints 10
</syntaxhighlight>

Pointers are both the source of C’s power and its danger.
They enable indirect access to arrays, functions, and structures,
making them indispensable in low-level development such as kernels and drivers.

However, incorrect address access can cause a '''Segmentation Fault''',
which is why C is often described as an “unsafe but predictable” language.

=== 3. Manual Memory Management ===
C does not include garbage collection (GC).
Memory allocation and deallocation are entirely the programmer’s responsibility.

<syntaxhighlight lang="c">
int *arr = malloc(sizeof(int) * 5);
...
free(arr);
</syntaxhighlight>

Functions like <code>malloc()</code>, <code>calloc()</code>, <code>realloc()</code>, and <code>free()</code>
are defined in the standard library <code>stdlib.h</code>.
This manual management model offers '''maximum performance''',
but improper use can lead to '''memory leaks''' or '''double-free errors'''.

Unlike modern languages with automatic memory management,
C’s model reflects its philosophy of total system resource control.

=== 4. Preprocessor ===
Before actual compilation, the C compiler performs a '''preprocessing''' phase.
This processes directives beginning with the <code>#</code> symbol,
providing significant structural flexibility to the language.

Common preprocessor directives include:
* <code>#include</code> – include external header files
* <code>#define</code> – define macros
* <code>#ifdef</code>, <code>#ifndef</code>, <code>#endif</code> – conditional compilation

Although technically just text substitution,
the preprocessor provides flexibility for C’s build system
and is essential for managing platform-specific code in large projects.

=== 5. Structured Programming ===
C is a procedural language that adopts block structures to implement '''structured programming'''.
It organizes control flow into functions
and provides explicit structures using <code>if</code> statements, loops (<code>for</code>, <code>while</code>),
and the <code>switch</code> statement.

<syntaxhighlight lang="c">
for (int i = 0; i < 5; i++) {
printf("%d\n", i);
}
</syntaxhighlight>

This design improved readability and maintainability,
breaking away from the linear control flow of [[B language]] and [[assembly language]],
and establishing the concept of “logical program composition.”

Later languages such as [[Pascal]], [[C++]], and [[Rust]] inherited this paradigm.

=== 6. Function-Centric Architecture ===
C follows the rule that “all code executes within a function.”
Every executable program must have a <code>main()</code> function,
and all functions must declare explicit return types and parameter lists.

<syntaxhighlight lang="c">
int add(int a, int b) {
return a + b;
}
</syntaxhighlight>

Since C89, the function '''prototype''' format was introduced,
allowing compilers to check argument types and improve type safety at call time.

C’s function architecture influenced later developments such as
[[C++]] methods, [[Rust]]’s functional model, and [[Wave]]’s chain APIs.

=== 7. Platform Independence ===
C was designed with the principle of “not being tied to any machine.”
Instead of using assembly code specific to a CPU or OS,
it enables hardware-independent source code that compilers translate appropriately.

Portability is one of C’s defining features,
allowing the same code to be recompiled and run on Windows, Linux, macOS, Unix, and more.

This is made possible by features like <code>sizeof</code>, <code>typedef</code>,
and the <code>std*</code> family of types, which abstract differences in memory size across platforms.

=== 8. Standard Library ===
The C Standard Library is a core component that extends the language’s functionality.
It includes file I/O, string manipulation, mathematical operations, and memory management,
enabling basic system-level tasks without OS-specific calls.

Key header files include:
* <code>stdio.h</code> – standard input/output
* <code>stdlib.h</code> – memory management and utilities
* <code>string.h</code> – string operations
* <code>math.h</code> – mathematical functions
* <code>time.h</code> – time-related utilities

The standard library is defined by the ISO standard,
and all C implementations are required to support it.

=== 9. Combination of Efficiency and Simplicity ===
C merges near-hardware efficiency with a readable high-level syntax.
As a result, C programs are both fast and lightweight while remaining human-readable.

This balance is one of the main reasons C has endured for over half a century,
remaining the standard for operating systems, compilers, embedded systems,
and all environments where “performance is everything.”

=== 10. Undefined Behavior ===
C explicitly allows certain undefined behaviors,
leaving room for compiler optimization.

Examples include pointer access beyond memory bounds
or using uninitialized variables — both considered “undefined behavior.”
This flexibility grants compiler implementers freedom,
but introduces potential risks to program stability.

It is both the reason for C’s remarkable performance
and the reason it demands a high level of responsibility from its programmers.

== Basic Structure ==
C programs follow the structural principle that “all code executes within functions.”
The most important entry point is the <code>main()</code> function,
where the program’s execution begins and ends.

C has a modular architecture.
Each source file (<code>.c</code>) contains one or more functions,
and header files (<code>.h</code>) are used to share declarations and interfaces between modules.

Every C program consists of three main components:
# '''Preprocessing section''' – directives such as <code>#include</code> and <code>#define</code>.
# '''Function section''' – <code>main()</code> and user-defined functions.
# '''Data section''' – global variables, constants, and structure definitions.

The following is the simplest example of a C program structure:

<syntaxhighlight lang="c">
#include <stdio.h>

int main(void) {
printf("Hello, World!\n");
return 0;
}
</syntaxhighlight>

The <code>#include</code> directive instructs the preprocessor to include the standard library,
and the <code>main()</code> function serves as the program’s entry point.
The C compiler always looks for and begins execution from <code>main()</code>.
This structure was later inherited by [[C++]], [[Rust]], and [[Wave]].

The structural simplicity of C became a standard paradigm
for compiler design, operating system development, and embedded systems programming.

=== Data Types ===
C’s data types are directly linked to the hardware memory model.
Each data type explicitly defines its '''storage size''', '''signness''', and permissible operations,
which determine both performance and memory efficiency.

The basic data types are as follows:

{| class="wikitable"
! Category !! Type !! Typical Size !! Description
|-
| Integer || <code>char</code> || 1 byte || Character or 8-bit integer
|-
| Integer || <code>short</code> || 2 bytes || Small integer
|-
| Integer || <code>int</code> || 4 bytes || Standard integer type
|-
| Integer || <code>long</code> || 4–8 bytes || Large integer
|-
| Floating-point || <code>float</code> || 4 bytes || Single-precision float
|-
| Floating-point || <code>double</code> || 8 bytes || Double-precision float
|-
| Boolean || <code>_Bool</code> || 1 byte || Introduced in C99
|}

Starting with the C99 standard,
<code>stdint.h</code> introduced fixed-width integer types such as
<code>int8_t</code>, <code>int32_t</code>, and <code>uint64_t</code>,
ensuring consistency across platforms.

C also supports composite data types:
* <code>struct</code> – groups multiple variables into a single logical unit.
* <code>union</code> – allows different types to share the same memory space.
* <code>enum</code> – defines a set of named constants.
* <code>typedef</code> – assigns aliases to existing types.

Although simple, C’s type system enables highly efficient code generation
that maps closely to hardware architecture.

=== Control Statements ===
C’s control statements define the logical flow of program execution.
Conditionals and loops are high-level abstractions of assembly-level branch instructions,
forming the foundation of all imperative programming logic.

* Conditionals: <code>if</code>, <code>else if</code>, <code>else</code>
* Selection: <code>switch</code> / <code>case</code>
* Loops: <code>for</code>, <code>while</code>, <code>do-while</code>
* Flow control: <code>break</code>, <code>continue</code>, <code>goto</code>

Example:

<syntaxhighlight lang="c">
for (int i = 0; i < 5; i++) {
if (i == 3) continue;
printf("%d\n", i);
}
</syntaxhighlight>

C’s control statements not only branch logic flow,
but also define the conceptual structure of imperative programming.
Because these statements map directly to machine instructions,
they enable compilers to perform efficient low-level optimizations.

=== Memory and Pointers ===
At the heart of C lies the ability to “manipulate memory addresses.”
This capability is what makes C not just a high-level language,
but a true '''system language'''.

A pointer is a variable that stores a memory address,
allowing indirect access or modification of another variable’s value.

<syntaxhighlight lang="c">
int x = 42;
int *ptr = &x;
printf("%d\n", *ptr);
</syntaxhighlight>

Here, <code>&</code> is the address-of operator,
and <code>*</code> is the dereference operator.
Thus, <code>*ptr</code> reads the actual memory value of <code>x</code>.

Through pointer operations, C allows low-level control such as:
* Direct memory access and modification
* Efficient array and string handling
* Function pointers for callback implementations
* Dynamic memory allocation (<code>malloc()</code>, <code>free()</code>)

This structure made C the optimal language for developing
operating systems, drivers, and firmware — domains that require direct hardware control.
However, incorrect memory access can cause immediate program crashes,
a risk considered part of C’s core philosophy:
“with freedom comes responsibility.”

=== Compilation Process ===
C is a '''compiled language''', meaning source code must be translated
into machine code before execution.
The compilation process consists of four main stages:

# '''Preprocessing'''
Handles directives such as <code>#include</code> and <code>#define</code>,
performing conditional compilation and macro expansion.
# '''Compilation'''
Translates preprocessed code into assembly code,
performing syntax analysis, type checking, and optimization.
# '''Assembly'''
Converts assembly code into object files (<code>.o</code>).
# '''Linking'''
Combines multiple object files and libraries
into the final executable (<code>.exe</code> or ELF binary).

Example of a typical build process on Linux:

<syntaxhighlight lang="bash">
gcc -E main.c -o main.i # Preprocessing
gcc -S main.i -o main.s # Compilation
gcc -c main.s -o main.o # Assembly
gcc main.o -o main # Linking
</syntaxhighlight>

This multi-stage structure not only reflects C’s simplicity
but also served as the foundation model for [[compiler]] design.
Most modern compilers are built upon this architecture.

Throughout the entire process, C maintains its essence
as a language that expresses programs directly at the hardware level.
As a result, C enables efficient use of system resources
while allowing developers to write readable and structured code —
earning its reputation as a “machine-friendly high-level language.”

== Standard Macros ==
The C standard defines a set of '''predefined macros''' that every implementation (compiler) must provide.
These macros convey information about the compiler environment, standard version, and platform,
helping programs behave correctly across different systems.

Standard macros are recognized during the '''preprocessing stage''',
and are determined at '''compile time''', not at runtime.
In essence, the preprocessor in C functions as a “compiler–language interface” for environment metadata.

=== Major Macro List ===
The following table summarizes the representative macros defined by the ISO/IEC C standard and their purposes.

{| class="wikitable"
! Macro Name !! Description !! Introduced In
|-
| <code>__STDC__</code> ||
Indicates that the compiler conforms to the ANSI/ISO C standard.
A value of 1 signifies a standard-compliant implementation. || C89
|-
| <code>__STDC_VERSION__</code> ||
Specifies the supported version of the C standard.
Examples:
<code>199409L</code> → C94
<code>199901L</code> → C99
<code>201112L</code> → C11
<code>201710L</code> → C17
<code>202311L</code> → C23 || C90 and later
|-
| <code>__STDC_HOSTED__</code> ||
Indicates whether the environment is hosted (with standard library support)
or freestanding (independent, e.g., kernel or embedded).
1 = hosted, 0 = freestanding. || C99
|-
| <code>__FILE__</code> ||
String literal of the current source filename being compiled. || C89
|-
| <code>__LINE__</code> ||
Current line number in the source file. Useful for debugging and logging. || C89
|-
| <code>__DATE__</code> ||
Compilation date as a string (e.g., "Oct 17 2025"). || C89
|-
| <code>__TIME__</code> ||
Compilation time as a string (e.g., "14:30:42"). || C89
|-
| <code>__func__</code> ||
Returns the current function name as a string.
<syntaxhighlight lang="c">
void test() {
printf("%s\n", __func__);
}
</syntaxhighlight>
The above code prints "test". || C99
|-
| <code>__STDC_NO_ATOMICS__</code> ||
Defined as 1 if the compiler does not support <code>_Atomic</code>. || C11
|-
| <code>__STDC_NO_THREADS__</code> ||
Defined if the compiler does not support the standard threads library (<code>threads.h</code>). || C11
|-
| <code>__STDC_UTF_16__</code>, <code>__STDC_UTF_32__</code> ||
Indicates support for UTF-16 and UTF-32 character types. || C11
|-
| <code>__STDC_ANALYZABLE__</code> ||
Indicates whether static analysis features are supported. || C23
|-
| <code>__STDC_VERSION_STDINT_H__</code> ||
Specifies the version of <code>stdint.h</code>,
confirming support for standard integer types. || C23
|}

In addition to these, many compilers (e.g., GCC, Clang, MSVC)
provide their own proprietary extension macros.
For example, GCC defines <code>__GNUC__</code>, and MSVC defines <code>_MSC_VER</code>.

=== Role and Significance of Macros ===
Standard macros are not mere constants —
they serve as a '''linguistic interface between the compiler and the program'''.
By providing “compile-time environment information” rather than runtime data,
they allow conditional compilation and environment-specific behavior.

For instance, the following code performs compiler-specific conditional builds:

<syntaxhighlight lang="c">
#ifdef __GNUC__
printf("Compiled with GCC\n");
#elif defined(_MSC_VER)
printf("Compiled with MSVC\n");
#else
printf("Unknown compiler\n");
#endif
</syntaxhighlight>

This mechanism is one of the key reasons C achieves portability and implementation independence.
The source code remains identical,
but compilers can generate machine code tailored to their environments
by '''exposing system information through preprocessor macros'''.

=== Philosophical Aspect ===
C’s standard macro system is not merely an extension of preprocessing capabilities —
it embodies the language’s core philosophy:
'''“The language should be small, and the implementation should be powerful.”'''
The language defines only minimal promises,
delegating environmental awareness to the compiler through the preprocessor.

This design directly influenced the build systems and compiler metadata handling
in later languages such as [[C++]], [[Rust]], and [[Wave]].
In particular, the <code>build.meta</code> system in the Wave language
is considered an evolved form of C’s preprocessor macro concept.

Ultimately, standard macros serve as an intermediary layer
linking the language, compiler, and hardware —
the very mechanism that has allowed C to maintain its '''portability and implementation freedom'''
for over half a century.

== Influence on Other Languages ==
C became the foundation of nearly all major programming languages developed since the late 20th century.
Its influence extends far beyond syntax—encompassing philosophy, memory models, compiler design, and error-handling paradigms.
In other words, C did not merely shape “the form of languages” but “the way languages think.”

=== 1. Direct Descendant Languages ===
Languages that directly inherited C’s structure and syntax are collectively called the “C family.”
They evolved from C’s syntax, expression structure, and the concepts of pointers or references.

* '''C++''' — developed by [[Bjarne Stroustrup]] in 1983.
It extended C by adding classes, objects, inheritance, templates, and other
'''object-oriented''' features.
Maintaining backward compatibility with C,
C++ achieved both hardware-level control and high-level abstraction—
earning the title “the language that expanded C’s philosophy.”

* '''Objective-C''' — created in the 1980s by [[Brad Cox]] and [[Tom Love]].
It combined C syntax with Smalltalk’s message-passing paradigm.
It became the foundation for [[NeXTSTEP]], [[macOS]], and [[iOS]],
defining Apple’s entire software ecosystem.

* '''C#''' — designed by [[Anders Hejlsberg]] at [[Microsoft]].
Built on C/C++ syntax, it was made to operate within the .NET Framework.
It preserved C’s syntactic familiarity while introducing garbage collection and runtime safety.

* '''Java''' — simplified C++’s syntax and abstracted its memory model.
Although it runs entirely within a virtual machine,
its control structures, operators, and type system remain largely C-like.

All of these languages share the common goal of being “C-like but safer than C.”

=== 2. Indirect Influence (Structure and Philosophy) ===
C’s influence extends into language design philosophies as well.

* '''Rust''' — inherited C’s low-level control philosophy,
but introduced ownership and compile-time validation
to ensure memory safety.
It is often described as “C without undefined behavior.”

* '''Go''' — retained C’s simplicity and explicit control structures
while modernizing the model for concurrency and network programming.
Since [[Ken Thompson]] and [[Rob Pike]]—key C developers—were involved,
Go is regarded as a spiritual successor to C.

* '''D language''' — maintained the performance of C and C++
while integrating modern abstractions and managed memory.
Strong interoperability with C code is one of its core traits.

* '''Swift''' — Apple’s successor to Objective-C,
replacing the C-based runtime with a modern type system.
Yet, its ABI and runtime architecture remain deeply influenced by C.

* '''Wave''' — a next-generation system language
that fundamentally inherits C’s memory model and compiler philosophy,
removing unnecessary complexity while experimenting with new syntax structures.
It preserves C’s core concept of “machine-oriented abstraction.”

=== 3. Conceptual Influence Inside Languages ===
C’s legacy also extends deep into the internal structure of modern languages.

* '''Operator Semantics''' —
Most languages directly reuse C’s operator system.
Examples include <code>++</code>, <code>--</code>, <code>==</code>, <code>!=</code>, and <code>+=</code>.
This syntax has effectively become the “industry standard operator notation.”

* '''Standard Library Architecture''' —
The structure of C’s headers—<code>stdio</code>, <code>stdlib</code>, and <code>string</code>—
laid the groundwork for modern module and package systems.

* '''Compilation Model''' —
The pipeline of preprocessing → compilation → assembly → linking
was inherited by [[C++]], [[Objective-C]], [[Rust]], and [[Wave]].

* '''Undefined Behavior Concept''' —
A philosophical legacy of C.
Some languages have eliminated it entirely (Rust, Swift),
while others retain it in restricted form (C++, D).

=== 4. Influence on Programming Culture ===
C’s impact is not limited to technology—it shaped programming culture itself.

* The “Hello, World!” program tradition
originated from the textbook ''The C Programming Language''.

* The concept that “a function is the fundamental unit of a program”
became a universal assumption in language design after C.

* C’s syntax became the shared grammar of education, research, and industry.
Today, most programmers can learn new languages quickly
because they share C-style syntax.

=== 5. Philosophical Legacy ===
C is not merely a starting point for functionality—
it became the '''philosophical benchmark''' for language design.

Its influence continues along three fundamental axes:
* '''The Power of Simplicity''' — remove unnecessary abstractions and focus on essentials.
* '''Freedom of Control''' — programmers, not the language, govern memory.
* '''The Philosophy of Efficiency''' — extract performance directly from hardware.

This enduring spirit explains why all modern languages, no matter how advanced,
are still compared and analyzed against C.

Ultimately, C is more than a programming language—
it is the '''coordinate system of programming language history'''.
All languages can be classified as either “before C” or “after C.”

== Modern Evaluation ==
Although C was designed in the early 1970s,
it remains one of the most important system programming languages in the world even in the 2020s.
Its relevance is not merely as a “historical legacy,”
but because the very foundation of modern computing still rests upon it.

=== 1. Continuing Industrial Influence ===
Most operating systems, embedded firmware, compilers, network stacks,
and database engines are either written in C or deeply interconnected with it.
Notable examples include the [[Linux]] kernel, [[Windows]] NT kernel,
the Darwin layer of [[macOS]], [[PostgreSQL]], [[MySQL]], [[Redis]], and [[Nginx]].

These systems are not ordinary applications—
they form the '''core infrastructure of modern computing''' upon which all other software depends.
Thus, C serves as the “foundational language upon which all higher-level languages operate.”

Today, most hardware APIs and OS interfaces use
the C ABI (Application Binary Interface) as a standard.
This makes C not just a language but a '''common language of systems'''.

=== 2. Technical Strengths and Reasons for Survival ===
C has endured for over half a century due to several technical advantages:

* '''Deterministic Performance''' –
With no garbage collection or runtime management,
C provides fully predictable execution time and memory usage—
essential for real-time systems, embedded devices, and kernel programming.

* '''Direct Hardware Control''' –
Through pointers and bit-level operations,
C allows direct access to memory, registers, and hardware devices—
a capability no modern high-level language can fully replace.

* '''Simple Compilation Model''' –
The consistent pipeline of preprocessing → compilation → assembly → linking
avoids complex runtimes or virtual machines,
resulting in higher portability and reliability.

* '''Transparency''' –
C code maps closely to actual machine instructions,
allowing programmers to predict memory layout and execution flow at the assembly level.

In short, C continues to dominate in three domains:
'''performance, simplicity, and control.'''

=== 3. Limitations and Criticisms ===
Despite its power, C has inherent limitations when faced with modern requirements.

* '''Lack of Memory Safety''' —
While pointer arithmetic and manual memory management offer flexibility,
they also introduce critical vulnerabilities such as buffer overflows,
invalid references (segfaults), and use-after-free errors.
Many security issues in the 2020s still originate from C code.

* '''Undefined Behavior''' —
The C standard intentionally leaves certain behaviors undefined to enable optimization,
but this leads to inconsistent results and compiler-dependent behavior.

* '''Limited Expressiveness''' —
C lacks modern abstractions such as object orientation, generics, and exception handling.
Writing large-scale systems often requires auxiliary languages or frameworks.

* '''Low Developer Productivity''' —
Manual memory management, pointer handling, and difficult debugging
make C less suitable for large-scale application development,
where speed of development and maintainability are key.

For these reasons, C is no longer a “universal language.”
Successor system languages such as [[Rust]], [[Go]], and [[Wave]]
have emerged to pursue both safety and efficiency simultaneously.

=== 4. Educational and Philosophical Value ===
Nevertheless, C remains the '''core language of computer science education'''.
This is not simply due to tradition—
C most directly reveals “how computers truly work.”

Learning C means learning memory structure, pointers, compiler mechanics,
and CPU instruction models.
Thus, universities, research institutes, and corporate training programs worldwide
continue to teach C as “the language upon which all others are built.”

From a philosophical standpoint,
C embodies the principle that “humans should master the machine, not be protected from it.”
Even as modern languages pursue automation and abstraction,
this philosophy explains why C endures.

=== 5. C’s Current Role ===
Today, C is no longer a language of rapid innovation.
Instead, it is valued for its “unchanging stability” and “established ecosystem.”
C does not aim to reinvent itself like modern languages;
most updates focus on refinement and standardization.

Since the [[C23]] standard, C continues to thrive alongside
advanced compiler infrastructures such as [[LLVM]], [[GCC]], and [[Clang]],
remaining the dominant language for kernels, networking, hardware control, and real-time systems.
Its role has shifted from “competitor among new languages”
to the enduring '''reference language for all others.'''

=== 6. Overall Evaluation ===
C remains both the foundation of modern software
and the philosophical axis of programming languages.
Its simplicity and risk are its greatest strengths,
and in terms of performance and control, it remains nearly unrivaled.

Ultimately, C is “an imperfect but fully comprehensible language,”
one that continues to define the very history of technology itself.

:''"C is both the origin and the gravity of programming languages."'' — TechPedia Editorial

== Related Articles ==
* [[Programming language]]
* [[B (programming language)]]
* [[C++]]
* [[Rust]]
* [[Wave]]
* [[Assembly language]]
* [[Compiler]]
* [[Operating system]]
* [[Unix]]

== References ==
* Dennis M. Ritchie & Brian W. Kernighan, ''The C Programming Language'', Prentice Hall, 1978.
* ISO/IEC 9899:2023 – Information technology — Programming languages — C (C23 Standard).
* ISO/IEC JTC1/SC22/WG14, [https://www.open-std.org/jtc1/sc22/wg14/ Official C Language Standard Committee Website].
* Bell Labs Computer Science Research Center, ''The Development of the C Language'', Dennis Ritchie, 1993.
* Bjarne Stroustrup, ''A History of C++: 1979–1991'', ACM SIGPLAN Notices, Vol. 28, No. 3, 1993.
* GNU Project, [https://gcc.gnu.org GCC (GNU Compiler Collection) Documentation].
* Clang Project, [https://clang.llvm.org Clang: C Language Family Frontend for LLVM].

[[Category:Programming languages]]
[[Category:C family]]
[[Category:System programming]]
[[Category:1970s software]]

C

2025-10-17T07:06:38Z

LunaStev:

{{Software infobox
| Name = C
| Logo = [[File:C_logo.png|120px]]
| Developer = Dennis Ritchie
| Released = 1972
| Latest release= C17 (2018)
| Extensions = .c, .h
| License = ISO/IEC 9899
| Website = https://www.open-std.org/jtc1/sc22/wg14/
}}

{{소프트웨어 정보
| 이름 = C
| 로고 = [[File:C_logo.png|120px]]
| 개발자 = '''Dennis Ritchie'''
| 출시일 = '''1972년'''
| 최신 버전 = '''C23 (2023년)'''
| 확장자 = ''.c'', ''.h''
| 라이선스 = '''ISO/IEC 9899'''
| 웹사이트 = https://www.open-std.org/jtc1/sc22/wg14/
}}

== Overview ==
'''C''' is a general-purpose programming language developed by '''Dennis Ritchie''' in the early 1970s at [[Bell Labs]].
At that time, Bell Labs — led by [[Ken Thompson]] and Ritchie — was developing a new operating system called [[Unix]],
and during this process, the limitations of assembly-based systems became apparent.

In the early 1970s, every computer had its own unique instruction set,
and porting an operating system or compiler required rewriting the entire codebase.
To solve this problem, Bell Labs set a goal to create a '''“portable operating system”''',
and to achieve this, they needed a new language that preserved the low-level control of assembly
while providing the structural expressiveness of a high-level language.

It was in this context that C was born.
Ritchie improved upon [[B (programming language)]], originally developed by Thompson,
introducing a more efficient and machine-friendly design.
C was first completed in 1972, and by 1973, the entire Unix kernel was successfully rewritten in C.
This event marked a major turning point in computer science history,
establishing C as a “system-level language.”

The greatest innovation of C lies in its philosophy as a '''“machine-oriented high-level language.”'''
This concept balances performance and abstraction
by allowing direct hardware control while organizing code
into functions and logical blocks.

C was designed around the following technical principles and philosophies:
* '''Low-level accessibility''' — direct memory manipulation via pointers (<code>*</code>) and the address operator (<code>&</code>).
* '''High-level structuring''' — logical code organization using conditionals, loops, functions, and structures.
* '''Minimalism''' — exclusion of unnecessary syntax, providing flexibility through simplicity.
* '''Portability''' — independence from specific hardware, enabling recompilation on different architectures.

Furthermore, C allows explicit hardware control
while maintaining simplicity and readability suitable for human developers.
Thanks to this balance, C became a foundational language across nearly all domains —
including compilers, operating systems, embedded systems, databases, and game engines.

The structural simplicity of C influenced the design of countless later languages.
[[C++]], [[Objective-C]], [[C#]], [[Rust]], [[Go]], and [[Wave]]
inherit and extend C’s syntax, memory model, function structure, and control flow.
As a result, C is regarded not merely as a language but as
an '''architectural prototype of programming language design.'''

Even today, C continues to serve as the standard for new language and system design,
remaining indispensable in operating system development, microcontroller programming,
and modern runtime implementations.
Its philosophical essence can be summarized by the following statement:

''“C is not just a programming language; it is a way of thinking about machines.”'' — Dennis Ritchie

== History ==
The evolution of C is not merely a story of syntax changes,
but a process intertwined with the development of operating systems, compilers, and hardware architecture.
Since its birth in the early 1970s, C has undergone several rounds of standardization,
laying the foundation for modern programming language design.

=== 1970s: Birth and Establishment ===
C was developed in 1972 at [[Bell Labs]] by '''Dennis Ritchie'''.
It was influenced by [[B (programming language)]] and [[BCPL]],
and designed to efficiently implement the [[Unix]] kernel on the PDP-11 computer system.

In 1973, when the Unix kernel was largely rewritten in C,
it became the first language to enable a “machine-independent operating system implementation.”
This milestone introduced the concept of portability to the software industry.

In 1978, Ritchie and [[Brian W. Kernighan]] published
''The C Programming Language'' (commonly known as '''K&R C''').
The book became a de facto standard,
and compiler developers worldwide used it as the basis for C implementations.

=== 1980s: The Beginning of Standardization (ANSI C) ===
As C was used across different environments,
syntax discrepancies between compilers grew significantly,
creating the need for standardization.

In 1983, the '''ANSI X3J11 Committee''' was formed
to establish an official standard specification,
and in 1989, the American National Standards Institute (ANSI) approved it.

This standard, known as '''ANSI X3.159-1989''', or simply '''ANSI C''' or '''C89''',
included the following major changes:
* Clear definition of function declaration format (prototype introduction)
* Addition of standard libraries <code>stdlib.h</code>, <code>string.h</code>, <code>assert.h</code>
* Improvements to enumerations (<code>enum</code>) and constant expressions
* Establishment of a standard I/O model (<code>stdio.h</code>)

ANSI C was later adopted as an international standard by ISO in 1990,
becoming '''ISO/IEC 9899:1990''', also known as '''C90'''.

=== 1990s: The Foundation of Modern Syntax (C99) ===
After the publication of the C89/C90 standard,
C needed to adapt to rapidly advancing hardware and compiler technologies.
This led to the release of a new standard, '''C99''', in 1999.

Key changes introduced in C99 include:
* Addition of <code>//</code> single-line comments (for C++ compatibility)
* Introduction of <code>inline</code> functions for performance optimization
* Support for Variable Length Arrays (VLA)
* New integer and complex types (<code>long long</code>, <code>_Complex</code>)
* Introduction of the <code>_Bool</code> type and <code>stdbool.h</code> header
* Provision of fixed-width integer types via <code>stdint.h</code> (e.g., <code>int32_t</code>)

During this era, C was widely used across embedded systems, network devices, and scientific computing,
establishing itself as an “industrial standard language.”

=== 2010s: Parallelism and Stability (C11, C17) ===
With the rise of multicore processors, C officially embraced parallel programming.
Released in 2011, '''C11''' became the first C standard to define a formal memory model and thread safety.

Core features of C11:
* Multithreading support (<code>_Thread_local</code>, <code>atomic</code> types)
* Static assertions (<code>_Static_assert</code>)
* Support for anonymous structs and unions
* Unicode expansion (<code>uchar.h</code>)
* Safer standard functions (<code>gets()</code> removed, <code>snprintf()</code> recommended)

C11 is widely regarded as the standard that defined “modern system-level C.”

In 2018, '''C17''' (ISO/IEC 9899:2018) was released,
not as a major feature update, but as a bug-fix and cleanup revision,
serving as a stable edition of C11.

=== 2020s: Modern Refinement (C23) ===
Published in 2023, '''C23''' preserves the 50-year-old philosophy of C
while incorporating select features from modern programming languages.

Major updates include:
* Introduction of the <code>nullptr</code> keyword (as a safer alternative to <code>NULL</code>)
* Standardization of UTF-8 string literals (<code>u8""</code>)
* Addition of the <code>typeof</code> operator and type inference expressions
* Support for <code>constexpr</code>-like constant evaluation
* Formal introduction of the <code>static_assert</code> syntax
* New <code>embed</code> directive for embedding binary data

C23 is regarded as “a practical evolution that modernizes C
without transforming it into an entirely new language,”
reflecting contemporary system and compiler design principles.

From its origins as the Unix development language in the 1970s
to its continued dominance in the 2020s,
C remains the '''standard language for operating systems, compilers, embedded systems, and hardware control'''.
Even after more than 50 years, its philosophy and structure have changed little,
and C continues to be “the simplest yet most fundamental programming language.”

== Philosophy ==
The design philosophy of C is not merely a collection of syntactic rules,
but rather a '''thought paradigm''' for understanding and manipulating computer hardware.
Dennis Ritchie defined C as a “machine-oriented high-level language,”
meaning that C is more than just a programming tool —
it represents a way of thinking about computers themselves.

The philosophy of C can be summarized in four core principles.

=== 1. Minimalism ===
C was designed under the principle of “providing only what is necessary.”
The language defines only a small set of core constructs,
leaving complex functionalities to be implemented directly by the programmer.
Automated abstractions such as garbage collection, classes, and exception handling
were deliberately excluded.

This philosophy grants programmers '''absolute freedom and responsibility''',
allowing powerful systems to be built from a small language core.
This design approach was later inherited by the [[Unix]] philosophy,
forming the basis of the principle “Do one thing and do it well.”

=== 2. Machine-Oriented Abstraction ===
C aims to be a high-level language capable of directly interacting with hardware.
This embodies the idea of '''“abstraction over machine code”''',
allowing programmers to control memory addresses, pointers, and register-level operations
without writing assembly code.

This concept goes beyond hardware-friendly syntax.
C encourages programmers to “understand the machine as it truly operates.”
Thus, C serves as a linguistic interface between hardware-level control
and higher-level logical structures.

=== 3. Portability and Implementation Freedom ===
C is a compiler-centered language —
that is, its implementation (the compiler) matters more than the language definition itself.
The language provides only minimal rules,
while compilers are responsible for adapting them to different platforms.

This structure realized the concept of “write once, run anywhere.”
One of C’s core ideas is that “a language should not be bound to a specific machine,”
which was the fundamental reason [[Unix]] could be ported across diverse hardware.

At the same time, C deliberately allows '''undefined behavior''',
maximizing compiler optimization and implementation freedom.
Although rare in modern languages,
this approach was key to preserving C’s performance and simplicity.

=== 4. Freedom and Responsibility ===
C gives nearly all control to the programmer.
Memory management, type casting, pointer arithmetic, and bit operations
are all left in the user’s hands.
Safety mechanisms are minimal,
and incorrect operations can immediately lead to crashes or undefined results.

This design reflects the philosophy of prioritizing “control over safety.”
C does not protect the programmer —
instead, it offers the same level of freedom as the machine itself.
This attitude solidified C’s identity as a “language equal to the machine.”

=== 5. Simplicity and Extensibility ===
C is simple, yet capable of expressing all forms of complexity.
Though the language is small, its composability allows developers to build
operating systems, compilers, graphics engines, and virtual machines.

This is why C is often described as “a small language, but a complete one.”
As Ritchie once said:
:''"C was not designed to hide the machine, but to express it efficiently."''

In other words, C’s simplicity is not a limitation of expression,
but a deliberate choice to maximize expressive efficiency.

=== 6. Philosophical Influence on Modern Languages ===
C’s philosophy became the foundational principle for many later languages:
* [[C++]] — added object-orientation and encapsulation atop C’s structure.
* [[Rust]] — inherited C’s performance and low-level control while reinforcing safety.
* [[Go]] — applied C’s simplicity and explicit control to modern system programming.
* [[Wave]] — reimagined and modernized C’s memory model and philosophy as a next-generation low-level language.

Thus, C has transcended its role as a language,
becoming the '''philosophical origin of programming languages'''.
Its core ideals — minimalism, portability, control, and simplicity —
remain the foundation of all modern system programming languages to this day.

== Key Features ==
C combines structural simplicity with low-level hardware control,
achieving both high performance and flexibility through the following technical features.

=== 1. Static Type System ===
In C, every variable’s data type must be explicitly declared at '''compile time'''.
This ensures predictable program behavior and allows the compiler
to determine memory size and operation methods in advance.

For example, operations between <code>int</code> and <code>float</code> are strictly distinguished at compile time,
executing without runtime overhead.
This '''statically analyzed design''' contrasts with modern dynamic languages,
enabling C to closely correspond to hardware operations.

C also supports both '''implicit casting''' and '''explicit casting''',
granting programmers full control over type conversions.
While powerful, these conversions may cause '''precision loss''' or '''overflow errors''' if misused.

=== 2. Pointers and Direct Memory Access ===
One of C’s most distinctive features is the concept of pointers.
A pointer holds a memory address as its value,
allowing direct reading and writing to memory regions.

<syntaxhighlight lang="c">
int a = 10;
int *p = &a;
printf("%d\n", *p); // prints 10
</syntaxhighlight>

Pointers are both the source of C’s power and its danger.
They enable indirect access to arrays, functions, and structures,
making them indispensable in low-level development such as kernels and drivers.

However, incorrect address access can cause a '''Segmentation Fault''',
which is why C is often described as an “unsafe but predictable” language.

=== 3. Manual Memory Management ===
C does not include garbage collection (GC).
Memory allocation and deallocation are entirely the programmer’s responsibility.

<syntaxhighlight lang="c">
int *arr = malloc(sizeof(int) * 5);
...
free(arr);
</syntaxhighlight>

Functions like <code>malloc()</code>, <code>calloc()</code>, <code>realloc()</code>, and <code>free()</code>
are defined in the standard library <code>stdlib.h</code>.
This manual management model offers '''maximum performance''',
but improper use can lead to '''memory leaks''' or '''double-free errors'''.

Unlike modern languages with automatic memory management,
C’s model reflects its philosophy of total system resource control.

=== 4. Preprocessor ===
Before actual compilation, the C compiler performs a '''preprocessing''' phase.
This processes directives beginning with the <code>#</code> symbol,
providing significant structural flexibility to the language.

Common preprocessor directives include:
* <code>#include</code> – include external header files
* <code>#define</code> – define macros
* <code>#ifdef</code>, <code>#ifndef</code>, <code>#endif</code> – conditional compilation

Although technically just text substitution,
the preprocessor provides flexibility for C’s build system
and is essential for managing platform-specific code in large projects.

=== 5. Structured Programming ===
C is a procedural language that adopts block structures to implement '''structured programming'''.
It organizes control flow into functions
and provides explicit structures using <code>if</code> statements, loops (<code>for</code>, <code>while</code>),
and the <code>switch</code> statement.

<syntaxhighlight lang="c">
for (int i = 0; i < 5; i++) {
printf("%d\n", i);
}
</syntaxhighlight>

This design improved readability and maintainability,
breaking away from the linear control flow of [[B language]] and [[assembly language]],
and establishing the concept of “logical program composition.”

Later languages such as [[Pascal]], [[C++]], and [[Rust]] inherited this paradigm.

=== 6. Function-Centric Architecture ===
C follows the rule that “all code executes within a function.”
Every executable program must have a <code>main()</code> function,
and all functions must declare explicit return types and parameter lists.

<syntaxhighlight lang="c">
int add(int a, int b) {
return a + b;
}
</syntaxhighlight>

Since C89, the function '''prototype''' format was introduced,
allowing compilers to check argument types and improve type safety at call time.

C’s function architecture influenced later developments such as
[[C++]] methods, [[Rust]]’s functional model, and [[Wave]]’s chain APIs.

=== 7. Platform Independence ===
C was designed with the principle of “not being tied to any machine.”
Instead of using assembly code specific to a CPU or OS,
it enables hardware-independent source code that compilers translate appropriately.

Portability is one of C’s defining features,
allowing the same code to be recompiled and run on Windows, Linux, macOS, Unix, and more.

This is made possible by features like <code>sizeof</code>, <code>typedef</code>,
and the <code>std*</code> family of types, which abstract differences in memory size across platforms.

=== 8. Standard Library ===
The C Standard Library is a core component that extends the language’s functionality.
It includes file I/O, string manipulation, mathematical operations, and memory management,
enabling basic system-level tasks without OS-specific calls.

Key header files include:
* <code>stdio.h</code> – standard input/output
* <code>stdlib.h</code> – memory management and utilities
* <code>string.h</code> – string operations
* <code>math.h</code> – mathematical functions
* <code>time.h</code> – time-related utilities

The standard library is defined by the ISO standard,
and all C implementations are required to support it.

=== 9. Combination of Efficiency and Simplicity ===
C merges near-hardware efficiency with a readable high-level syntax.
As a result, C programs are both fast and lightweight while remaining human-readable.

This balance is one of the main reasons C has endured for over half a century,
remaining the standard for operating systems, compilers, embedded systems,
and all environments where “performance is everything.”

=== 10. Undefined Behavior ===
C explicitly allows certain undefined behaviors,
leaving room for compiler optimization.

Examples include pointer access beyond memory bounds
or using uninitialized variables — both considered “undefined behavior.”
This flexibility grants compiler implementers freedom,
but introduces potential risks to program stability.

It is both the reason for C’s remarkable performance
and the reason it demands a high level of responsibility from its programmers.

== Basic Structure ==
C programs follow the structural principle that “all code executes within functions.”
The most important entry point is the <code>main()</code> function,
where the program’s execution begins and ends.

C has a modular architecture.
Each source file (<code>.c</code>) contains one or more functions,
and header files (<code>.h</code>) are used to share declarations and interfaces between modules.

Every C program consists of three main components:
# '''Preprocessing section''' – directives such as <code>#include</code> and <code>#define</code>.
# '''Function section''' – <code>main()</code> and user-defined functions.
# '''Data section''' – global variables, constants, and structure definitions.

The following is the simplest example of a C program structure:

<syntaxhighlight lang="c">
#include <stdio.h>

int main(void) {
printf("Hello, World!\n");
return 0;
}
</syntaxhighlight>

The <code>#include</code> directive instructs the preprocessor to include the standard library,
and the <code>main()</code> function serves as the program’s entry point.
The C compiler always looks for and begins execution from <code>main()</code>.
This structure was later inherited by [[C++]], [[Rust]], and [[Wave]].

The structural simplicity of C became a standard paradigm
for compiler design, operating system development, and embedded systems programming.

=== Data Types ===
C’s data types are directly linked to the hardware memory model.
Each data type explicitly defines its '''storage size''', '''signness''', and permissible operations,
which determine both performance and memory efficiency.

The basic data types are as follows:

{| class="wikitable"
! Category !! Type !! Typical Size !! Description
|-
| Integer || <code>char</code> || 1 byte || Character or 8-bit integer
|-
| Integer || <code>short</code> || 2 bytes || Small integer
|-
| Integer || <code>int</code> || 4 bytes || Standard integer type
|-
| Integer || <code>long</code> || 4–8 bytes || Large integer
|-
| Floating-point || <code>float</code> || 4 bytes || Single-precision float
|-
| Floating-point || <code>double</code> || 8 bytes || Double-precision float
|-
| Boolean || <code>_Bool</code> || 1 byte || Introduced in C99
|}

Starting with the C99 standard,
<code>stdint.h</code> introduced fixed-width integer types such as
<code>int8_t</code>, <code>int32_t</code>, and <code>uint64_t</code>,
ensuring consistency across platforms.

C also supports composite data types:
* <code>struct</code> – groups multiple variables into a single logical unit.
* <code>union</code> – allows different types to share the same memory space.
* <code>enum</code> – defines a set of named constants.
* <code>typedef</code> – assigns aliases to existing types.

Although simple, C’s type system enables highly efficient code generation
that maps closely to hardware architecture.

=== Control Statements ===
C’s control statements define the logical flow of program execution.
Conditionals and loops are high-level abstractions of assembly-level branch instructions,
forming the foundation of all imperative programming logic.

* Conditionals: <code>if</code>, <code>else if</code>, <code>else</code>
* Selection: <code>switch</code> / <code>case</code>
* Loops: <code>for</code>, <code>while</code>, <code>do-while</code>
* Flow control: <code>break</code>, <code>continue</code>, <code>goto</code>

Example:

<syntaxhighlight lang="c">
for (int i = 0; i < 5; i++) {
if (i == 3) continue;
printf("%d\n", i);
}
</syntaxhighlight>

C’s control statements not only branch logic flow,
but also define the conceptual structure of imperative programming.
Because these statements map directly to machine instructions,
they enable compilers to perform efficient low-level optimizations.

=== Memory and Pointers ===
At the heart of C lies the ability to “manipulate memory addresses.”
This capability is what makes C not just a high-level language,
but a true '''system language'''.

A pointer is a variable that stores a memory address,
allowing indirect access or modification of another variable’s value.

<syntaxhighlight lang="c">
int x = 42;
int *ptr = &x;
printf("%d\n", *ptr);
</syntaxhighlight>

Here, <code>&</code> is the address-of operator,
and <code>*</code> is the dereference operator.
Thus, <code>*ptr</code> reads the actual memory value of <code>x</code>.

Through pointer operations, C allows low-level control such as:
* Direct memory access and modification
* Efficient array and string handling
* Function pointers for callback implementations
* Dynamic memory allocation (<code>malloc()</code>, <code>free()</code>)

This structure made C the optimal language for developing
operating systems, drivers, and firmware — domains that require direct hardware control.
However, incorrect memory access can cause immediate program crashes,
a risk considered part of C’s core philosophy:
“with freedom comes responsibility.”

=== Compilation Process ===
C is a '''compiled language''', meaning source code must be translated
into machine code before execution.
The compilation process consists of four main stages:

# '''Preprocessing'''
Handles directives such as <code>#include</code> and <code>#define</code>,
performing conditional compilation and macro expansion.
# '''Compilation'''
Translates preprocessed code into assembly code,
performing syntax analysis, type checking, and optimization.
# '''Assembly'''
Converts assembly code into object files (<code>.o</code>).
# '''Linking'''
Combines multiple object files and libraries
into the final executable (<code>.exe</code> or ELF binary).

Example of a typical build process on Linux:

<syntaxhighlight lang="bash">
gcc -E main.c -o main.i # Preprocessing
gcc -S main.i -o main.s # Compilation
gcc -c main.s -o main.o # Assembly
gcc main.o -o main # Linking
</syntaxhighlight>

This multi-stage structure not only reflects C’s simplicity
but also served as the foundation model for [[compiler]] design.
Most modern compilers are built upon this architecture.

Throughout the entire process, C maintains its essence
as a language that expresses programs directly at the hardware level.
As a result, C enables efficient use of system resources
while allowing developers to write readable and structured code —
earning its reputation as a “machine-friendly high-level language.”

== Standard Macros ==
The C standard defines a set of '''predefined macros''' that every implementation (compiler) must provide.
These macros convey information about the compiler environment, standard version, and platform,
helping programs behave correctly across different systems.

Standard macros are recognized during the '''preprocessing stage''',
and are determined at '''compile time''', not at runtime.
In essence, the preprocessor in C functions as a “compiler–language interface” for environment metadata.

=== Major Macro List ===
The following table summarizes the representative macros defined by the ISO/IEC C standard and their purposes.

{| class="wikitable"
! Macro Name !! Description !! Introduced In
|-
| <code>__STDC__</code> ||
Indicates that the compiler conforms to the ANSI/ISO C standard.
A value of 1 signifies a standard-compliant implementation. || C89
|-
| <code>__STDC_VERSION__</code> ||
Specifies the supported version of the C standard.
Examples:
<code>199409L</code> → C94
<code>199901L</code> → C99
<code>201112L</code> → C11
<code>201710L</code> → C17
<code>202311L</code> → C23 || C90 and later
|-
| <code>__STDC_HOSTED__</code> ||
Indicates whether the environment is hosted (with standard library support)
or freestanding (independent, e.g., kernel or embedded).
1 = hosted, 0 = freestanding. || C99
|-
| <code>__FILE__</code> ||
String literal of the current source filename being compiled. || C89
|-
| <code>__LINE__</code> ||
Current line number in the source file. Useful for debugging and logging. || C89
|-
| <code>__DATE__</code> ||
Compilation date as a string (e.g., "Oct 17 2025"). || C89
|-
| <code>__TIME__</code> ||
Compilation time as a string (e.g., "14:30:42"). || C89
|-
| <code>__func__</code> ||
Returns the current function name as a string.
<syntaxhighlight lang="c">
void test() {
printf("%s\n", __func__);
}
</syntaxhighlight>
The above code prints "test". || C99
|-
| <code>__STDC_NO_ATOMICS__</code> ||
Defined as 1 if the compiler does not support <code>_Atomic</code>. || C11
|-
| <code>__STDC_NO_THREADS__</code> ||
Defined if the compiler does not support the standard threads library (<code>threads.h</code>). || C11
|-
| <code>__STDC_UTF_16__</code>, <code>__STDC_UTF_32__</code> ||
Indicates support for UTF-16 and UTF-32 character types. || C11
|-
| <code>__STDC_ANALYZABLE__</code> ||
Indicates whether static analysis features are supported. || C23
|-
| <code>__STDC_VERSION_STDINT_H__</code> ||
Specifies the version of <code>stdint.h</code>,
confirming support for standard integer types. || C23
|}

In addition to these, many compilers (e.g., GCC, Clang, MSVC)
provide their own proprietary extension macros.
For example, GCC defines <code>__GNUC__</code>, and MSVC defines <code>_MSC_VER</code>.

=== Role and Significance of Macros ===
Standard macros are not mere constants —
they serve as a '''linguistic interface between the compiler and the program'''.
By providing “compile-time environment information” rather than runtime data,
they allow conditional compilation and environment-specific behavior.

For instance, the following code performs compiler-specific conditional builds:

<syntaxhighlight lang="c">
#ifdef __GNUC__
printf("Compiled with GCC\n");
#elif defined(_MSC_VER)
printf("Compiled with MSVC\n");
#else
printf("Unknown compiler\n");
#endif
</syntaxhighlight>

This mechanism is one of the key reasons C achieves portability and implementation independence.
The source code remains identical,
but compilers can generate machine code tailored to their environments
by '''exposing system information through preprocessor macros'''.

=== Philosophical Aspect ===
C’s standard macro system is not merely an extension of preprocessing capabilities —
it embodies the language’s core philosophy:
'''“The language should be small, and the implementation should be powerful.”'''
The language defines only minimal promises,
delegating environmental awareness to the compiler through the preprocessor.

This design directly influenced the build systems and compiler metadata handling
in later languages such as [[C++]], [[Rust]], and [[Wave]].
In particular, the <code>build.meta</code> system in the Wave language
is considered an evolved form of C’s preprocessor macro concept.

Ultimately, standard macros serve as an intermediary layer
linking the language, compiler, and hardware —
the very mechanism that has allowed C to maintain its '''portability and implementation freedom'''
for over half a century.

== Influence on Other Languages ==
C became the foundation of nearly all major programming languages developed since the late 20th century.
Its influence extends far beyond syntax—encompassing philosophy, memory models, compiler design, and error-handling paradigms.
In other words, C did not merely shape “the form of languages” but “the way languages think.”

=== 1. Direct Descendant Languages ===
Languages that directly inherited C’s structure and syntax are collectively called the “C family.”
They evolved from C’s syntax, expression structure, and the concepts of pointers or references.

* '''C++''' — developed by [[Bjarne Stroustrup]] in 1983.
It extended C by adding classes, objects, inheritance, templates, and other
'''object-oriented''' features.
Maintaining backward compatibility with C,
C++ achieved both hardware-level control and high-level abstraction—
earning the title “the language that expanded C’s philosophy.”

* '''Objective-C''' — created in the 1980s by [[Brad Cox]] and [[Tom Love]].
It combined C syntax with Smalltalk’s message-passing paradigm.
It became the foundation for [[NeXTSTEP]], [[macOS]], and [[iOS]],
defining Apple’s entire software ecosystem.

* '''C#''' — designed by [[Anders Hejlsberg]] at [[Microsoft]].
Built on C/C++ syntax, it was made to operate within the .NET Framework.
It preserved C’s syntactic familiarity while introducing garbage collection and runtime safety.

* '''Java''' — simplified C++’s syntax and abstracted its memory model.
Although it runs entirely within a virtual machine,
its control structures, operators, and type system remain largely C-like.

All of these languages share the common goal of being “C-like but safer than C.”

=== 2. Indirect Influence (Structure and Philosophy) ===
C’s influence extends into language design philosophies as well.

* '''Rust''' — inherited C’s low-level control philosophy,
but introduced ownership and compile-time validation
to ensure memory safety.
It is often described as “C without undefined behavior.”

* '''Go''' — retained C’s simplicity and explicit control structures
while modernizing the model for concurrency and network programming.
Since [[Ken Thompson]] and [[Rob Pike]]—key C developers—were involved,
Go is regarded as a spiritual successor to C.

* '''D language''' — maintained the performance of C and C++
while integrating modern abstractions and managed memory.
Strong interoperability with C code is one of its core traits.

* '''Swift''' — Apple’s successor to Objective-C,
replacing the C-based runtime with a modern type system.
Yet, its ABI and runtime architecture remain deeply influenced by C.

* '''Wave''' — a next-generation system language
that fundamentally inherits C’s memory model and compiler philosophy,
removing unnecessary complexity while experimenting with new syntax structures.
It preserves C’s core concept of “machine-oriented abstraction.”

=== 3. Conceptual Influence Inside Languages ===
C’s legacy also extends deep into the internal structure of modern languages.

* '''Operator Semantics''' —
Most languages directly reuse C’s operator system.
Examples include <code>++</code>, <code>--</code>, <code>==</code>, <code>!=</code>, and <code>+=</code>.
This syntax has effectively become the “industry standard operator notation.”

* '''Standard Library Architecture''' —
The structure of C’s headers—<code>stdio</code>, <code>stdlib</code>, and <code>string</code>—
laid the groundwork for modern module and package systems.

* '''Compilation Model''' —
The pipeline of preprocessing → compilation → assembly → linking
was inherited by [[C++]], [[Objective-C]], [[Rust]], and [[Wave]].

* '''Undefined Behavior Concept''' —
A philosophical legacy of C.
Some languages have eliminated it entirely (Rust, Swift),
while others retain it in restricted form (C++, D).

=== 4. Influence on Programming Culture ===
C’s impact is not limited to technology—it shaped programming culture itself.

* The “Hello, World!” program tradition
originated from the textbook ''The C Programming Language''.

* The concept that “a function is the fundamental unit of a program”
became a universal assumption in language design after C.

* C’s syntax became the shared grammar of education, research, and industry.
Today, most programmers can learn new languages quickly
because they share C-style syntax.

=== 5. Philosophical Legacy ===
C is not merely a starting point for functionality—
it became the '''philosophical benchmark''' for language design.

Its influence continues along three fundamental axes:
* '''The Power of Simplicity''' — remove unnecessary abstractions and focus on essentials.
* '''Freedom of Control''' — programmers, not the language, govern memory.
* '''The Philosophy of Efficiency''' — extract performance directly from hardware.

This enduring spirit explains why all modern languages, no matter how advanced,
are still compared and analyzed against C.

Ultimately, C is more than a programming language—
it is the '''coordinate system of programming language history'''.
All languages can be classified as either “before C” or “after C.”

== Modern Evaluation ==
Although C was designed in the early 1970s,
it remains one of the most important system programming languages in the world even in the 2020s.
Its relevance is not merely as a “historical legacy,”
but because the very foundation of modern computing still rests upon it.

=== 1. Continuing Industrial Influence ===
Most operating systems, embedded firmware, compilers, network stacks,
and database engines are either written in C or deeply interconnected with it.
Notable examples include the [[Linux]] kernel, [[Windows]] NT kernel,
the Darwin layer of [[macOS]], [[PostgreSQL]], [[MySQL]], [[Redis]], and [[Nginx]].

These systems are not ordinary applications—
they form the '''core infrastructure of modern computing''' upon which all other software depends.
Thus, C serves as the “foundational language upon which all higher-level languages operate.”

Today, most hardware APIs and OS interfaces use
the C ABI (Application Binary Interface) as a standard.
This makes C not just a language but a '''common language of systems'''.

=== 2. Technical Strengths and Reasons for Survival ===
C has endured for over half a century due to several technical advantages:

* '''Deterministic Performance''' –
With no garbage collection or runtime management,
C provides fully predictable execution time and memory usage—
essential for real-time systems, embedded devices, and kernel programming.

* '''Direct Hardware Control''' –
Through pointers and bit-level operations,
C allows direct access to memory, registers, and hardware devices—
a capability no modern high-level language can fully replace.

* '''Simple Compilation Model''' –
The consistent pipeline of preprocessing → compilation → assembly → linking
avoids complex runtimes or virtual machines,
resulting in higher portability and reliability.

* '''Transparency''' –
C code maps closely to actual machine instructions,
allowing programmers to predict memory layout and execution flow at the assembly level.

In short, C continues to dominate in three domains:
'''performance, simplicity, and control.'''

=== 3. Limitations and Criticisms ===
Despite its power, C has inherent limitations when faced with modern requirements.

* '''Lack of Memory Safety''' —
While pointer arithmetic and manual memory management offer flexibility,
they also introduce critical vulnerabilities such as buffer overflows,
invalid references (segfaults), and use-after-free errors.
Many security issues in the 2020s still originate from C code.

* '''Undefined Behavior''' —
The C standard intentionally leaves certain behaviors undefined to enable optimization,
but this leads to inconsistent results and compiler-dependent behavior.

* '''Limited Expressiveness''' —
C lacks modern abstractions such as object orientation, generics, and exception handling.
Writing large-scale systems often requires auxiliary languages or frameworks.

* '''Low Developer Productivity''' —
Manual memory management, pointer handling, and difficult debugging
make C less suitable for large-scale application development,
where speed of development and maintainability are key.

For these reasons, C is no longer a “universal language.”
Successor system languages such as [[Rust]], [[Go]], and [[Wave]]
have emerged to pursue both safety and efficiency simultaneously.

=== 4. Educational and Philosophical Value ===
Nevertheless, C remains the '''core language of computer science education'''.
This is not simply due to tradition—
C most directly reveals “how computers truly work.”

Learning C means learning memory structure, pointers, compiler mechanics,
and CPU instruction models.
Thus, universities, research institutes, and corporate training programs worldwide
continue to teach C as “the language upon which all others are built.”

From a philosophical standpoint,
C embodies the principle that “humans should master the machine, not be protected from it.”
Even as modern languages pursue automation and abstraction,
this philosophy explains why C endures.

=== 5. C’s Current Role ===
Today, C is no longer a language of rapid innovation.
Instead, it is valued for its “unchanging stability” and “established ecosystem.”
C does not aim to reinvent itself like modern languages;
most updates focus on refinement and standardization.

Since the [[C23]] standard, C continues to thrive alongside
advanced compiler infrastructures such as [[LLVM]], [[GCC]], and [[Clang]],
remaining the dominant language for kernels, networking, hardware control, and real-time systems.
Its role has shifted from “competitor among new languages”
to the enduring '''reference language for all others.'''

=== 6. Overall Evaluation ===
C remains both the foundation of modern software
and the philosophical axis of programming languages.
Its simplicity and risk are its greatest strengths,
and in terms of performance and control, it remains nearly unrivaled.

Ultimately, C is “an imperfect but fully comprehensible language,”
one that continues to define the very history of technology itself.

:''"C is both the origin and the gravity of programming languages."'' — TechPedia Editorial

== Related Articles ==
* [[Programming language]]
* [[B (programming language)]]
* [[C++]]
* [[Rust]]
* [[Wave]]
* [[Assembly language]]
* [[Compiler]]
* [[Operating system]]
* [[Unix]]

== References ==
* Dennis M. Ritchie & Brian W. Kernighan, ''The C Programming Language'', Prentice Hall, 1978.
* ISO/IEC 9899:2023 – Information technology — Programming languages — C (C23 Standard).
* ISO/IEC JTC1/SC22/WG14, [https://www.open-std.org/jtc1/sc22/wg14/ Official C Language Standard Committee Website].
* Bell Labs Computer Science Research Center, ''The Development of the C Language'', Dennis Ritchie, 1993.
* Bjarne Stroustrup, ''A History of C++: 1979–1991'', ACM SIGPLAN Notices, Vol. 28, No. 3, 1993.
* GNU Project, [https://gcc.gnu.org GCC (GNU Compiler Collection) Documentation].
* Clang Project, [https://clang.llvm.org Clang: C Language Family Frontend for LLVM].

[[Category:Programming languages]]
[[Category:C family]]
[[Category:System programming]]
[[Category:1970s software]]

Zeta

2025-10-15T00:48:23Z

LunaStev: Created page with "{{Software Infobox | Name = Zeta | Developer = Voxon Development | ReleaseDate = In development | LatestVersion = None | Extension = .zeta | License = GPL-3.0 | Website = https://github.com/Voxon-Development/zeta-lang }} '''Zeta''' is a programming language developed in 2025 by '''Wildered''' from Egypt. == History == * 2025: Currently in development. == Key Features == == Example Code == <syntaxhighlight lang="c"> main() {..."

{{Software Infobox
| Name = Zeta
| Developer = Voxon Development
| ReleaseDate = In development
| LatestVersion = None
| Extension = .zeta
| License = GPL-3.0
| Website = https://github.com/Voxon-Development/zeta-lang
}}

'''Zeta''' is a programming language developed in 2025 by '''Wildered''' from Egypt.

== History ==
* 2025: Currently in development.

== Key Features ==

== Example Code ==

<syntaxhighlight lang="c">
main() {
println("Hello, World!!!")
println(49)

let something: boolean = true
if (something) {
let num: i32 = 49 + (23 * 39)
println_int(num)
}
}
</syntaxhighlight>

== Applications ==

== See Also ==
* [[Programming languages]]
* [[Rust]]

== References ==
* Voxon Development GitHub

[[Category:Programming languages]]

Programming languages

2025-10-15T00:47:26Z

LunaStev: /* Z */

= Programming languages =
A '''programming language''' is a formal system designed to express computations,
instruct computers, and describe algorithms.
Each language has its own syntax, semantics, and execution model,
allowing humans to represent procedures that machines can perform.

== Overview ==
Programming languages are central to computer science.
They serve as a bridge between human thought and machine execution,
enabling the expression of algorithms, data manipulation, and interaction with hardware and software.

They are used in education, research, industry, and even art,
playing a fundamental role in the advancement of human knowledge and technology.

== List of programming languages ==
Below is a list of programming languages covered in TechPedia.
The list is ordered alphabetically (numbers → A–Z → others).
When creating a new language page, add it here.

=== 0–9 ===
* [[1C:Enterprise]]
* [[4th Dimension]]

=== A ===
* [[Ada]]
* [[ALGOL]]
* [[APL]]
* [[Assembly language]]

=== B ===
* [[B]]
* [[BASIC]]
* [[Brainfuck]]

=== C ===
* [[C]]
* [[C/AL]]
* [[C Shell]]
* [[C--]]
* [[C++]]
* [[C*]]
* [[C＃]]
* [[Caché ObjectScript]]
* [[Caml]]
* [[Carbon]]
* [[Cayenne]]
* [[Cecil]]
* [[CESIL]]
* [[Céu]]
* [[Ceylon]]
* [[CFEngine]]
* [[CFML]]
* [[Cg]]
* [[Ch]]
* [[Chapel]]
* [[Charm]]
* [[CHILL]]
* [[CHIP-8]]
* [[ChucK]]
* [[Cilk]]
* [[Claire]]
* [[Clean]]
* [[Clipper]]
* [[CLIPS]]
* [[CLIST]]
* [[Clojure]]
* [[CLU]]
* [[CMS-2]]
* [[COBOL]]
* [[CobolScript]]
* [[Cobra]]
* [[CoffeeScript]]
* [[ColdFusion]]
* [[COMAL]]
* [[COMIT]]
* [[Common Intermediate]]
* [[Common Lisp]]
* [[COMPASS]]
* [[Component Pascal]]
* [[COMTRAN]]
* [[Concurrent Pascal]]
* [[Constraint Handling Rules]]
* [[Control Language]]
* [[Coq]]
* [[CORAL]]
* [[CorVision]]
* [[COWSEL]]
* [[CPL]]
* [[Cryptol]]
* [[Crystal]]
* [[Csound]]
* [[Cuneiform]]
* [[Curl]]
* [[Curry]]
* [[Cybil]]
* [[Cyclone]]
* [[Cypher Query Language]]
* [[Cython]]

=== D ===
* [[D]]
* [[Dart]]

=== E ===
* [[Eiffel]]
* [[Elixir]]
* [[Erlang]]

=== F ===
* [[F＃]]
* [[Fortran]]

=== G ===
* [[Go]]
* [[Groovy]]

=== H ===
* [[Haskell]]
* [[HTML]] (markup language)

=== J ===
* [[Java]]
* [[JavaScript]]
* [[Julia]]

=== K ===
* [[Kotlin]]

=== L ===
* [[Lisp]]
* [[Lua]]

=== M ===
* [[MATLAB]]
* [[Modula-2]]

=== N ===
* [[Nim]]

=== O ===
* [[Objective-C]]
* [[OCaml]]

=== P ===
* [[Pascal]]
* [[Perl]]
* [[PHP]]
* [[Prolog]]
* [[Python]]

=== R ===
* [[R]]
* [[Ruby]]
* [[Rust]]

=== S ===
* [[Scala]]
* [[Scheme]]
* [[Smalltalk]]
* [[Swift]]

=== T ===
* [[Tcl]]
* [[TypeScript]]

=== V ===
* [[V]]
* [[Verilog]]
* [[VHDL]]
* [[Visual Basic]]

=== W ===
* [[Wave]]
* [[Whitespace]]

=== Z ===
* [[Zeta]]
* [[Zig]]

=== Others ===
* [[Malbolge]]
* [[INTERCAL]]
* [[Esoteric programming languages]]

== See also ==
* [[Computer science fundamentals]]
* [[Compilers & tools]]
* [[Operating systems]]

----

''This article both introduces programming languages and serves as the central hub for the language list on TechPedia.''

Wave

2025-10-15T00:38:34Z

LunaStev: /* See Also */

{{Software Infobox
| Name = Wave
| Logo = [[File:Wave_logo.png|120px]]
| Developer = LunaStev
| ReleaseDate = January 14, 2025
| LatestVersion = v0.1.4-pre-beta
| Extension = .wave
| License = LSD License
| Website = https://wave-lang.dev/
}}

'''Wave''' is a programming language developed by '''LunaStev''' on January 14, 2025.

== History ==
* 2024: Wave development began.
* 2025: v0.1.4-pre-beta released.

== Key Features ==
The Wave language has the following characteristics:

== Example Code ==
This is an example from the official Wave website.

<syntaxhighlight lang="kotlin">
fun main() {
var name: str = "Wave";
let year: i32 = 2024; // immutable

println("Language: {}, Year: {}", name, year);
}
</syntaxhighlight>

== Applications ==
Wave is being developed with the intention of being used in areas such as:
* Systems programming (OS, drivers, embedded software)
* Web backend development

== See Also ==
* [[Programming languages]]
* [[C]]
* [[Rust]]

== References ==
* [https://github.com/wavefnd/Wave/ Wave GitHub repository]
* [https://wave-lang.dev/ Official Wave website]

[[Category:Programming languages]]

Wave

2025-10-15T00:37:50Z

LunaStev:

{{Software Infobox
| Name = Wave
| Logo = [[File:Wave_logo.png|120px]]
| Developer = LunaStev
| ReleaseDate = January 14, 2025
| LatestVersion = v0.1.4-pre-beta
| Extension = .wave
| License = LSD License
| Website = https://wave-lang.dev/
}}

'''Wave''' is a programming language developed by '''LunaStev''' on January 14, 2025.

== History ==
* 2024: Wave development began.
* 2025: v0.1.4-pre-beta released.

== Key Features ==
The Wave language has the following characteristics:

== Example Code ==
This is an example from the official Wave website.

<syntaxhighlight lang="kotlin">
fun main() {
var name: str = "Wave";
let year: i32 = 2024; // immutable

println("Language: {}, Year: {}", name, year);
}
</syntaxhighlight>

== Applications ==
Wave is being developed with the intention of being used in areas such as:
* Systems programming (OS, drivers, embedded software)
* Web backend development

== See Also ==
* [[Programming language]]
* [[C (programming language)]]
* [[Rust]]

== References ==
* [https://github.com/wavefnd/Wave/ Wave GitHub repository]
* [https://wave-lang.dev/ Official Wave website]

[[Category:Programming languages]]

Template:Software Infobox

2025-10-15T00:35:33Z

LunaStev: Created page with "<includeonly> {| class="infobox" style="float:right; clear:right; margin:0 0 1em 1em; width:280px; font-size:90%; line-height:1.5em; background:#f8f9fa;" |- ! colspan="2" style="text-align:center; font-size:120%; background:#e9ecef;" | {{{Name|{{PAGENAME}}}}} |- | colspan="2" style="text-align:center;" | {{{Logo|}}} |- ! Developer | {{{Developer|}}} |- ! Initial release | {{{ReleaseDate|}}} |- ! Latest version | {{{LatestVersion|}}} |- ! File extension | {{{Extension|}}}..."

<includeonly>
{| class="infobox" style="float:right; clear:right; margin:0 0 1em 1em; width:280px; font-size:90%; line-height:1.5em; background:#f8f9fa;"
|-
! colspan="2" style="text-align:center; font-size:120%; background:#e9ecef;" | {{{Name|{{PAGENAME}}}}}
|-
| colspan="2" style="text-align:center;" | {{{Logo|}}}
|-
! Developer
| {{{Developer|}}}
|-
! Initial release
| {{{ReleaseDate|}}}
|-
! Latest version
| {{{LatestVersion|}}}
|-
! File extension
| {{{Extension|}}}
|-
! License
| {{{License|}}}
|-
! Website
| [{{{Website|}}} Official site]
|}
</includeonly>
<noinclude>
== Usage ==
Place the following at the top of the article:

<pre>
{{Software Infobox
| Name = C
| Logo = [[File:C_logo.png|120px]]
| Developer = Dennis Ritchie
| ReleaseDate = 1972
| LatestVersion = C17 (2018)
| Extension = .c, .h
| License = ISO/IEC standard
| Website = https://www.open-std.org/jtc1/sc22/wg14/
}}
</pre>
</noinclude>

Wave

2025-10-15T00:35:26Z

LunaStev:

{{Software Infobox
| Name = C
| Logo = [[File:C_logo.png|120px]]
| Developer = Dennis Ritchie
| ReleaseDate = 1972
| LatestVersion = C17 (2018)
| Extension = .c, .h
| License = ISO/IEC standard
| Website = https://www.open-std.org/jtc1/sc22/wg14/
}}

Wave

2025-10-15T00:34:46Z

Programming languages

2025-10-15T00:33:03Z

LunaStev:

= Programming languages =
A '''programming language''' is a formal system designed to express computations,
instruct computers, and describe algorithms.
Each language has its own syntax, semantics, and execution model,
allowing humans to represent procedures that machines can perform.

== Overview ==
Programming languages are central to computer science.
They serve as a bridge between human thought and machine execution,
enabling the expression of algorithms, data manipulation, and interaction with hardware and software.

They are used in education, research, industry, and even art,
playing a fundamental role in the advancement of human knowledge and technology.

== List of programming languages ==
Below is a list of programming languages covered in TechPedia.
The list is ordered alphabetically (numbers → A–Z → others).
When creating a new language page, add it here.

=== 0–9 ===
* [[1C:Enterprise]]
* [[4th Dimension]]

=== A ===
* [[Ada]]
* [[ALGOL]]
* [[APL]]
* [[Assembly language]]

=== B ===
* [[B]]
* [[BASIC]]
* [[Brainfuck]]

=== C ===
* [[C]]
* [[C/AL]]
* [[C Shell]]
* [[C--]]
* [[C++]]
* [[C*]]
* [[C＃]]
* [[Caché ObjectScript]]
* [[Caml]]
* [[Carbon]]
* [[Cayenne]]
* [[Cecil]]
* [[CESIL]]
* [[Céu]]
* [[Ceylon]]
* [[CFEngine]]
* [[CFML]]
* [[Cg]]
* [[Ch]]
* [[Chapel]]
* [[Charm]]
* [[CHILL]]
* [[CHIP-8]]
* [[ChucK]]
* [[Cilk]]
* [[Claire]]
* [[Clean]]
* [[Clipper]]
* [[CLIPS]]
* [[CLIST]]
* [[Clojure]]
* [[CLU]]
* [[CMS-2]]
* [[COBOL]]
* [[CobolScript]]
* [[Cobra]]
* [[CoffeeScript]]
* [[ColdFusion]]
* [[COMAL]]
* [[COMIT]]
* [[Common Intermediate]]
* [[Common Lisp]]
* [[COMPASS]]
* [[Component Pascal]]
* [[COMTRAN]]
* [[Concurrent Pascal]]
* [[Constraint Handling Rules]]
* [[Control Language]]
* [[Coq]]
* [[CORAL]]
* [[CorVision]]
* [[COWSEL]]
* [[CPL]]
* [[Cryptol]]
* [[Crystal]]
* [[Csound]]
* [[Cuneiform]]
* [[Curl]]
* [[Curry]]
* [[Cybil]]
* [[Cyclone]]
* [[Cypher Query Language]]
* [[Cython]]

=== D ===
* [[D]]
* [[Dart]]

=== E ===
* [[Eiffel]]
* [[Elixir]]
* [[Erlang]]

=== F ===
* [[F＃]]
* [[Fortran]]

=== G ===
* [[Go]]
* [[Groovy]]

=== H ===
* [[Haskell]]
* [[HTML]] (markup language)

=== J ===
* [[Java]]
* [[JavaScript]]
* [[Julia]]

=== K ===
* [[Kotlin]]

=== L ===
* [[Lisp]]
* [[Lua]]

=== M ===
* [[MATLAB]]
* [[Modula-2]]

=== N ===
* [[Nim]]

=== O ===
* [[Objective-C]]
* [[OCaml]]

=== P ===
* [[Pascal]]
* [[Perl]]
* [[PHP]]
* [[Prolog]]
* [[Python]]

=== R ===
* [[R]]
* [[Ruby]]
* [[Rust]]

=== S ===
* [[Scala]]
* [[Scheme]]
* [[Smalltalk]]
* [[Swift]]

=== T ===
* [[Tcl]]
* [[TypeScript]]

=== V ===
* [[V]]
* [[Verilog]]
* [[VHDL]]
* [[Visual Basic]]

=== W ===
* [[Wave]]
* [[Whitespace]]

=== Z ===
* [[Zig]]

=== Others ===
* [[Malbolge]]
* [[INTERCAL]]
* [[Esoteric programming languages]]

== See also ==
* [[Computer science fundamentals]]
* [[Compilers & tools]]
* [[Operating systems]]

----

''This article both introduces programming languages and serves as the central hub for the language list on TechPedia.''

Template:Software infobox

2025-09-07T13:32:01Z

LunaStev: Created page with "<includeonly> {| class="infobox" style="float:right; clear:right; margin:0 0 1em 1em; width:280px; font-size:90%; line-height:1.5em; background:#f8f9fa;" |- ! colspan="2" style="text-align:center; font-size:120%; background:#e9ecef;" | {{{Name|{{PAGENAME}}}}} |- | colspan="2" style="text-align:center;" | {{{Logo|}}} |- ! Developer | {{{Developer|}}} |- ! First released | {{{Released|}}} |- ! Latest version | {{{Latest release|}}} |- ! Filename extensions | {{{Extensions|..."

<includeonly>
{| class="infobox" style="float:right; clear:right; margin:0 0 1em 1em; width:280px; font-size:90%; line-height:1.5em; background:#f8f9fa;"
|-
! colspan="2" style="text-align:center; font-size:120%; background:#e9ecef;" | {{{Name|{{PAGENAME}}}}}
|-
| colspan="2" style="text-align:center;" | {{{Logo|}}}
|-
! Developer
| {{{Developer|}}}
|-
! First released
| {{{Released|}}}
|-
! Latest version
| {{{Latest release|}}}
|-
! Filename extensions
| {{{Extensions|}}}
|-
! License
| {{{License|}}}
|-
! Website
| [{{{Website|}}} Official site]
|}
</includeonly>
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== Usage ==
Place at the top of an article like this:

<pre>
{{Software infobox
| Name = C
| Logo = [[File:C_logo.png|120px]]
| Developer = Dennis Ritchie
| Released = 1972
| Latest release= C17 (2018)
| Extensions = .c, .h
| License = ISO/IEC standard
| Website = https://www.open-std.org/jtc1/sc22/wg14/
}}
</pre>
</noinclude>

C

2025-09-07T13:31:54Z

LunaStev:

C

2025-09-07T13:29:01Z

LunaStev: Created page with "= C = '''C''' is a programming language created in the early 1970s by '''Dennis Ritchie''' at Bell Labs. It was originally designed to implement the Unix operating system, but quickly grew beyond that role. Even today, C is often called the "mother of modern programming languages" because of its lasting influence. == History == * 1969: Early Unix was written in assembly language. * 1972: Dennis Ritchie developed C, building on the B language. * 1978: Brian Ker..."

= C =
'''C''' is a programming language created in the early 1970s by '''Dennis Ritchie''' at Bell Labs.
It was originally designed to implement the Unix operating system, but quickly grew beyond that role.
Even today, C is often called the "mother of modern programming languages" because of its lasting influence.

== History ==
* 1969: Early Unix was written in assembly language.
* 1972: Dennis Ritchie developed C, building on the B language.
* 1978: Brian Kernighan and Dennis Ritchie published ''The C Programming Language'' (K&R C), which became the de facto reference.
* Later standardized by ANSI and ISO, with revisions continuing to this day.

== Key features ==
C is known for:
* Concise syntax and expressive power
* Low-level memory access (pointers)
* Portability across hardware platforms
* Standard library providing I/O, string handling, math, and more

== Example ==
The classic "Hello, World!" program:

<syntaxhighlight lang="c">
#include <stdio.h>

int main(void) {
printf("Hello, World!\n");
return 0;
}
</syntaxhighlight>

Though simple, this snippet shows the essence of C:
`#include` pulls in libraries, and `main` is the entry point of execution.

== Applications ==
C remains in use across many fields:
* Operating systems (Unix, Linux, parts of Windows)
* Embedded systems (IoT, microcontrollers, consumer electronics)
* Network software and database engines
* Implementations of other languages (Python, Lua, Ruby have C cores)

== See also ==
* [[Programming languages]]
* [[C++]]
* [[Rust]]
* [[Wave]]

== References ==
* Dennis M. Ritchie & Brian W. Kernighan, ''The C Programming Language'' (1978).
* ISO/IEC 9899:2018 C Standard.

[[Category:Programming languages]]

Programming languages

2025-09-07T13:28:42Z

LunaStev: Created page with "= Programming languages = A '''programming language''' is a formal system designed to express computations, instruct computers, and describe algorithms. Each language has its own syntax, semantics, and execution model, allowing humans to represent procedures that machines can perform. == Overview == Programming languages are central to computer science. They serve as a bridge between human thought and machine execution, enabling the expression of algorithms,..."

= Programming languages =
A '''programming language''' is a formal system designed to express computations,
instruct computers, and describe algorithms.
Each language has its own syntax, semantics, and execution model,
allowing humans to represent procedures that machines can perform.

== Overview ==
Programming languages are central to computer science.
They serve as a bridge between human thought and machine execution,
enabling the expression of algorithms, data manipulation, and interaction with hardware and software.

They are used in education, research, industry, and even art,
playing a fundamental role in the advancement of human knowledge and technology.

== List of programming languages ==
Below is a list of programming languages covered in TechPedia.
The list is ordered alphabetically (numbers → A–Z → others).
When creating a new language page, add it here.

=== 0–9 ===
* [[1C:Enterprise]]
* [[4th Dimension]]

=== A ===
* [[Ada]]
* [[ALGOL]]
* [[APL]]
* [[Assembly language]]

=== B ===
* [[B]]
* [[BASIC]]
* [[Brainfuck]]

=== C ===
* [[C]]
* [[C++]]
* [[C#]]
* [[COBOL]]

=== D ===
* [[D]]
* [[Dart]]

=== E ===
* [[Eiffel]]
* [[Elixir]]
* [[Erlang]]

=== F ===
* [[F#]]
* [[Fortran]]

=== G ===
* [[Go]]
* [[Groovy]]

=== H ===
* [[Haskell]]
* [[HTML]] (markup language)

=== J ===
* [[Java]]
* [[JavaScript]]
* [[Julia]]

=== K ===
* [[Kotlin]]

=== L ===
* [[Lisp]]
* [[Lua]]

=== M ===
* [[MATLAB]]
* [[Modula-2]]

=== N ===
* [[Nim]]

=== O ===
* [[Objective-C]]
* [[OCaml]]

=== P ===
* [[Pascal]]
* [[Perl]]
* [[PHP]]
* [[Prolog]]
* [[Python]]

=== R ===
* [[R]]
* [[Ruby]]
* [[Rust]]

=== S ===
* [[Scala]]
* [[Scheme]]
* [[Smalltalk]]
* [[Swift]]

=== T ===
* [[Tcl]]
* [[TypeScript]]

=== V ===
* [[V]]
* [[Verilog]]
* [[VHDL]]
* [[Visual Basic]]

=== W ===
* [[Wave]]
* [[Whitespace]]

=== Z ===
* [[Zig]]

=== Others ===
* [[Malbolge]]
* [[INTERCAL]]
* [[Esoteric programming languages]]

== See also ==
* [[Computer science fundamentals]]
* [[Compilers & tools]]
* [[Operating systems]]

----

''This article both introduces programming languages and serves as the central hub for the language list on TechPedia.''

TechPedia:Editing guidelines

2025-09-07T13:28:08Z

LunaStev: Created page with "= Editing Guidelines = Welcome to '''TechPedia'''! This page explains the rules and standards for contributing to the wiki. All editors are expected to follow these guidelines to maintain quality, accuracy, and readability. == 1. General principles == * Articles must be written in a '''neutral, objective tone'''. * Content should be '''fact-based and verifiable'''. Avoid speculation, personal opinions, or unverified claims. * Each article should strive for '''c..."

= Editing Guidelines =

Welcome to '''TechPedia'''!
This page explains the rules and standards for contributing to the wiki.
All editors are expected to follow these guidelines to maintain quality, accuracy, and readability.

== 1. General principles ==
* Articles must be written in a '''neutral, objective tone'''.
* Content should be '''fact-based and verifiable'''. Avoid speculation, personal opinions, or unverified claims.
* Each article should strive for '''clarity, conciseness, and accessibility''' for readers at all levels.

== 2. Sources and references ==
* Provide references for technical claims, historical notes, or performance comparisons whenever possible.
* Acceptable sources include:
* Academic papers, textbooks, or university lectures.
* Official documentation (e.g. ISO, IEEE, W3C, RFCs).
* Vendor/maintainer documentation (e.g. GNU, Linux Foundation, official project sites).
* Blogs, forums, or personal notes are discouraged unless written by recognized experts.

== 3. Article structure ==
* Start with a '''lead section''' that briefly explains the topic.
* Use clear section headings (e.g. == History ==, == Features ==, == Usage ==).
* Provide examples when relevant (e.g. code snippets). Use the <code><nowiki><syntaxhighlight lang="c">...</syntaxhighlight></nowiki></code> tag for code blocks.
* Add "See also" and "References" sections at the end.

== 4. Language and formatting ==
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* "operating system" (not OS unless already defined).
* "C++ standard library" (not STL unless explained).
* Write in '''American English''' for the English wiki.
* Use wiki markup:
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* External links: <code><nowiki>[https://example.com Example]</nowiki></code>
* Bold: <code><nowiki>'''bold'''</nowiki></code>, italics: <code><nowiki>''italics''</nowiki></code>.

== 5. What not to do ==
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== 6. Collaboration ==
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* Use the "Discussion" tab to resolve conflicts.
* Major changes should be discussed before editing heavily used pages.

== 7. Licensing ==
* '''All contributions to TechPedia are dedicated to the public domain (CC0).'''
* This means every edit is a true public good: free for anyone to use, copy, modify, or redistribute without any restrictions.
* No attribution, no conditions, no limitations.
* By editing, you agree that your contributions are released as unrestricted public domain knowledge.

----

''By following these guidelines, TechPedia remains a reliable and professional public knowledge base for computer science and technology.''

Main Page

2025-09-07T13:27:41Z

LunaStev:

= Welcome to TechPedia =
''An open encyclopedia for computer science and modern technology.''

== 🌐 Read in other language ==
* [https://ko.techpedia.wiki 한국어 위키 →]

== About TechPedia ==
TechPedia is a free and collaborative wiki dedicated to computer science and technology.
Our goal is to provide accurate, reliable, and up-to-date knowledge covering:

* Programming languages – from C and C++ to modern ecosystems like Rust and Wave.
* Computer science fundamentals – algorithms, data structures, and complexity theory.
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== Explore by Topic ==
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== How to Contribute ==
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* See the [[TechPedia:Editing guidelines|editing guidelines]].
* Share reliable references from standards, academic papers, or official docs.

----

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