onexit()

create a list of functions to be called when the program terminates normally

Synopsis:

#include <stdlib.h>
onexit_t onexit( onexit_t func );

Description:

The onexit() function is passed the address of function func to be called when the program terminates normally. Successive calls to onexit() create a list of functions that will be executed on a "last-in, first-out" basis. No more than 32 functions can be registered with the onexit() function.

The functions have no parameters and don't return values.

The functions registered with onexit() aren't called when the program is terminated by a call to _exit(). The onexit() function isn't an ANSI function. The ANSI standard function atexit() does the same thing as onexit(), and should be used instead when ANSI portability is a concern.

Returns:

func if the registration succeeds, and NULL if it fails.

Examples:

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

int  main( void )
  {
    void func1(void), func2(void), func3(void);

    onexit( func1 );
    onexit( func2 );
    onexit( func3 );
    printf( "Do this first.\n" );
    return( EXIT_SUCCESS );
  }

void func1(void) { printf( "last.\n" ); }
void func2(void) { printf( "this " ); }
void func3(void) { printf( "Do " ); }

produces the output:

Do this first.
Do this last.

Classification:

WATCOM

See also:

abort(), atexit(), exit(), _exit()