C programming language

The C programming language was derived from an earlier programming language called B, itself derived from BCPL. There was next a short-lived intermediary language called 'NB', or New B. C can be crisply, and aptly, described as 'BCPL with types and terser syntax'. The syntax arrived with B; types were added in the step to NB; and C added such things as structures.

A number of object-oriented languages have been influenced by C, including Objective-C, C++, D, Vala.

Dialects

There are two popular dialects, the original was K&R C, which spread with the original C compiler, and pcc, the portable C compiler. Later there was an ANSI standard for the C language, usually referred to as 'ANSI C'.

The C language evolved continuously starting in 1972. Some milestones:

• 1972 - Primeval C - no struct, automatic variables can't be initialized.
• 1973 - preprocessor added.
• 1976? - Typesetter C - introduced long, unsigned, typedef, union, and changed =+ etc to +=.
• 1978 - K&R C
• 1989 - ANSI C

hello world

Ancient

char *hello "hello"; /* No = for initialization. */

main (argc, argv)
int argc;               /* Parameter declarations as in K&R. */
char **argv;
{
        char *world;    /* Auto variables can't be initialized. */
        world = "world";
        cprint ("%s %s\n", hello, world);       /* No stdio yet. */
}

K&R

#include <stdio.h>
main(argc,argv)
int argc;
char **argv;
{
        printf("Hello World\n");
        exit (0);
}

ANSI C

#include <stdio.h>
int main(int argc, char *argv[])
{
        printf("Hello World\n");
        return 0;
}

Compilers

• Borland C
• Watcom C

See also

• Programming in C - A Tutorial - wonderfully clear and concise
• Old C Changes - some history of the development
• C Changes
• Typesetter C - one important stage
• Standard I/O library - I/O is not formally part of the language
• PDP-11 C stack operation

External links

• The C Programming Language - a later BSTJ paper describing C
• The Evolution of C - Past and Future - covers things after K+R
• Dennis M. Ritchie - see section "C and its immediate ancestors"
  • C Reference Manual - the version from V6
  • The Development of the C Language (PDF) - Ritchie paper with details of the early evolution
  • Primeval C - Ritchie notes on some C software archaeology
  • The C Language Calling Sequence - interesting note by DMR and SCJ
  • Recent Changes to C - November 15, 1978 - a few post-K+R changes
• “A damn stupid thing to do” — the origins of C - starts at the beginning, with the CPL story