C (programming language)

C (programming language)
Paradigm	Imperative programming, Procedural programming
Designer	Dennis Ritchie
Developer	Bell Labs
Typing	Static typing, Weak typing
Influenced	C++, C Sharp (programming language), Objective-C, Java (programming language), Go (programming language)

C (programming language). C is a general-purpose, procedural computer programming language supporting structured programming, lexical variable scope, and recursion, with a static type system. Designed by Dennis Ritchie at Bell Labs in the early 1970s, it was created to construct utilities running on Unix. It has since become one of the most widely used programming languages, profoundly influencing the development of software and operating systems.

History

The development of C began in 1972 at Bell Labs, led by Dennis Ritchie as a successor to the B (programming language), which was itself derived from BCPL. Its primary purpose was to facilitate the re-implementation of the Unix operating system kernel, which was originally written in assembly language. The language's portability and efficiency were quickly recognized, leading to the publication of the influential book The C Programming Language by Brian Kernighan and Ritchie in 1978. The widespread adoption of Unix on PDP-11 and later VAX systems cemented C's role in systems programming. By the 1980s, it had become the dominant language for implementing operating systems like Microsoft Windows and application software.

Features

C provides a rich set of features that offer low-level access to computer memory while maintaining a relatively high-level syntax. It is characterized by its minimalistic runtime support, making it suitable for embedded systems and firmware. The language uses a compiler to translate source code directly into efficient machine code for various central processing unit architectures. Key features include a comprehensive set of operator (programming)s, a simple I/O (input/output) model, and the ability to manipulate memory addresses directly through pointer (computer programming). This combination allows programmers to write highly efficient code for tasks ranging from operating system kernels to graphical user interface libraries.

Syntax

The syntax of C has influenced many subsequent languages, including C++, Java (programming language), and C Sharp (programming language). Program structure is based on functions and statement blocks delimited by curly braces. Control flow is managed through constructs like if statement, while loop, for loop, and switch statement. Data is organized into fundamental types such as integer (computer science), floating-point arithmetic, and character (computing), which can be aggregated into array (data structure)s and struct (C programming language)s. The language famously uses the semicolon to terminate statements and pointer (computer programming) arithmetic for direct memory manipulation.

Memory management

Memory management in C is primarily manual, granting the programmer precise control over computer memory allocation and deallocation. The standard library provides functions like malloc and free (C) for dynamic memory allocation on the heap (data structure). Variables can be stored in different memory segments: automatic variables on the call stack, static variables in a fixed data segment, and register (computer architecture) for hinting at fast storage. This manual control, while powerful, places the responsibility for avoiding errors like buffer overflow and memory leak squarely on the programmer, a characteristic that has driven the development of tools like Valgrind and languages like Rust (programming language).

Uses

C is ubiquitously used in areas where performance and control are paramount. It is the foundational language for most operating system kernels, including Linux, macOS, and components of Microsoft Windows. It is essential in embedded systems, powering the firmware for devices from microcontrollers in Internet of Things appliances to the flight software for the Mars rovers. Major applications, such as the Oracle Database and parts of the Python (programming language) interpreter, are implemented in it. Furthermore, it serves as the common intermediate language for many compilers and is used to create graphics processing unit drivers and video game engines like id Tech.

Standards

The standardization of C has been crucial for its portability and longevity. The first de facto standard was established by the book The C Programming Language. In 1989, the American National Standards Institute published the first official standard, known as ANSI C or C89, which was subsequently adopted by the International Organization for Standardization as ISO/IEC 9899:1990. This was followed by major revisions: C99, which added features like variable-length arrays and complex number support; C11, introducing multithreading support and alignment features; and C17/C18, a minor revision. The current standard, C23 (C standard revision), continues to evolve the language, with ongoing work by committees like JTC1/SC22.

Category:Programming languages Category:C programming language family Category:Systems programming languages