atexit

Processes the specified function at exit.

intatexit(void(__cdecl*func)(void));

For additional compatibility information, see Compatibility in the Introduction.

Libraries

To generate an ANSI-compliant application, use the ANSI-standard atexit function (rather than the similar _onexit function).

Return Value

atexit returns 0 if successful, or a nonzero value if an error occurs.

Parameter

func

Function to be called

Remarks

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 in LIFO (last-in-first-out) order. The functions passed to atexit cannot take parameters. atexit and _onexit use the heap to hold the register of functions. Thus, the number of functions that can be registered is limited only by heap memory.

Example

/* ATEXIT.C: This program pushes four functions onto
 * the stack of functions to be executed when atexit
 * is called. When the program exits, these programs
 * are executed on a "last in, first out" basis.
 */

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

void fn1( void ), fn2( void ), fn3( void ), fn4( void );

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

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

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

void fn3()
{
   printf( "is " );
}

void fn4()
{
   printf( "This " );
}

Output

This is executed first.
This is executed next.

Process and Environment Control Routines

See Also   abort, exit, _onexit