atexit(S)                      6 January 1993                      atexit(S)


 Name

    atexit - register function to be called at termination

 Syntax


    cc  . . .  -lc


    #include <stdlib.h>

    int atexit(func)
    void (*func)(void);


 Description

    The atexit function is passed the address of a function (func) to be
    called when the program terminates normally. Successive calls to atexit
    create a register of functions that are executed ``last in, first out.''
    No more than 32 functions can be registered with atexit. The functions
    passed to atexit cannot take parameters.

 Return value

    atexit returns zero on success or -1 on failure.

 See also

    abort(S), exit(S)

 Example


    #include <stdlib.h>
    #include <stdio.h>

    main( )
     {
             int fn1( ), fn2( ), fn3( ), fn4( );
             atexit(fn1);
             atexit(fn2);
             atexit(fn3);
             atexit(fn4);
             printf("This is executed first.\n");
     }

    int fn1( )
     {
             printf("next.\n");
     }

    int fn2( )
     {
             printf("executed ");
     }

     int fn3( )
     {
             printf("is ");
     }

    int fn4( )
     {
             printf("This ");
     }

    Output:

      This is executed first.
      This is executed next.

    This program pushes four functions onto the stack of functions to be exe-
    cuted when atexit is called. When the program exits, these programs are
    executed on a last-in, first-out basis.

 Standards conformance

    atexit is conformant with:
    ANSI X3.159-1989 Programming Language -- C.