Registers a routine to be called at exit time.
_onexit_t _onexit( _onexit_t func );
| Routine | Required Header | Compatibility |
| _onexit | <stdlib.h> | Win 95, Win NT |
For additional compatibility information, see Compatibility in the Introduction.
Libraries
| LIBC.LIB | Single thread static library, retail version |
| LIBCMT.LIB | Multithread static library, retail version |
| MSVCRT.LIB | Import library for MSVCRT.DLL, retail version |
Return Value
_onexit returns a pointer to the function if successful, or NULL if there is no space to store the function pointer.
Parameter
func
Pointer to function to be called at exit
Remarks
The _onexit function is passed the address of a function (func) to be called when the program terminates normally. Successive calls to _onexit create a register of functions that are executed in LIFO (last-in-first-out) order. The functions passed to _onexit cannot take parameters.
_onexit is a Microsoft extension. For ANSI portability use atexit.
Example
/* ONEXIT.C */
#include <stdlib.h>
#include <stdio.h>
/* Prototypes */
int fn1(void), fn2(void), fn3(void), fn4 (void);
void main( void )
{
_onexit( fn1 );
_onexit( fn2 );
_onexit( fn3 );
_onexit( fn4 );
printf( "This is executed first.\n" );
}
int fn1()
{
printf( "next.\n" );
return 0;
}
int fn2()
{
printf( "executed " );
return 0;
}
int fn3()
{
printf( "is " );
return 0;
}
int fn4()
{
printf( "This " );
return 0;
}
Output
This is executed first.
This is executed next.