C programming language

The C programming language was derived from an earlier language called B. There was a short-lived intermediary language called NB, or New B.

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 a ANSI standard to the C language, and it's usually refered to as just 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;
}

See also

• PDP-11 C stack operation

External links

• The Development of the C Language - Ritchie paper with details of the early evolution
  • HTML version
  • PDF version
• Primeval C - Ritchie notes on some software archaeology