Стандарты языка программирования C

Standards for the C programming language
the programming language standard

ANSI C, ISO C, and Standard C are successive standards for the C programming language published by the American National Standards Institute (ANSI) and ISO/IEC JTC 1/SC 22/WG 14 of the International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC). Historically, the names referred specifically to the original and best supported version of the standard (known as C89 or C90). Software developers writing in C are encouraged to conform to the standards, as doing so helps portability between compilers.

The first standard for C was published by ANSI. Although this document was subsequently adopted by ISO/IEC and subsequent revisions published by ISO/IEC have been adopted by ANSI, "ANSI C" is still used to refer to the standard. While some software developers use the term ISO C, others are standards body neutral and use Standard C.

Informal specification in 1978 (Brian Kernighan and Dennis Ritchie book The C Programming Language).

In 1983, the American National Standards Institute formed a committee, X3J11, to establish a standard specification of C. In 1985, the first Standard Draft was released, sometimes referred to as C85. In 1986, another Draft Standard was released, sometimes referred to as C86. The prerelease Standard C was published in 1988, and sometimes referred to as C88.

The ANSI standard was completed in 1989 and ratified as ANSI X3.159 1989 "Programming Language C." This version of the language is often referred to as "ANSI C". Later on sometimes the label "C89" is used to distinguish it from C90 but using the same labeling method.

The same standard as C89 was ratified by ISO/IEC as ISO/IEC 9899:1990, with only formatting changes, which is sometimes referred to as C90. Therefore, the terms "C89" and "C90" refer to essentially the same language. This standard has been withdrawn by both ANSI/INCITS and ISO/IEC.

as of 2018, "C17" is the current standard for the C programming language. C17 addresses defects in C11 without introducing new language features.

C23 is the informal name for the next major C language standard revision.

ANSI C is now supported by almost all the widely used compilers. GCC and Clang are two major C compilers popular today, both based on the C11 with updates including changes from later specifications such as C17. Any source code written only in standard C and without any hardware dependent assumptions is virtually guaranteed to compile correctly on any platform with a conforming C implementation. Without such precautions, most programs may compile only on a certain platform or with a particular compiler, due, for example, to the use of non standard libraries, such as GUI libraries, or to the reliance on compiler or platform specific attributes such as the exact size of certain data types and byte endianness.