C89

C89, commonly called ANSI C, is the first standardized version of the C programming language. It was published in 1989 by the American National Standards Institute (ANSI) as X3.4-1989 and subsequently adopted internationally as ISO/IEC 9899:1990, forming the basis of ISO C90.

Development and scope: The standard emerged from the ANSI X3J11 committee with input from ISO/IEC JTC1/SC22/WG14, replacing the de facto K&R C with a formal specification of language syntax, semantics, and a standard library. It aimed to improve portability of C programs across different compilers and platforms.

Key features: The standard defines the core language and a standard library, including headers such as stdio.h, stdlib.h, string.h, and math.h. It specifies types, operators, control structures, and function interfaces, with emphasis on portability. It supports both old-style (K&R) and ANSI-style function declarations to ease transition from K&R C.

Limitations and legacy: Compared with later standards, C89 lacks features added in C99 and beyond and does not standardize boolean types; it uses /* */ for comments rather than //, which came later. Nevertheless, it provided a portable basis that shaped subsequent ISO C revisions and remains influential in legacy code and compiler implementations.