_onexit
, _onexit_m
Registers a routine to be called at exit time.
Syntax
_onexit_t _onexit(
_onexit_t function
);
_onexit_t_m _onexit_m(
_onexit_t_m function
);
Parameters
function
Pointer to a function to be called at exit.
Return value
_onexit
returns a pointer to the function if successful or NULL
if there's no space to store the function pointer.
Remarks
The _onexit
function is passed the address of a function (function
) 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
can't take parameters.
In the case when _onexit
is called from within a DLL, routines registered with _onexit
run when the DLL is unloaded, after DllMain
is called with DLL_PROCESS_DETACH
.
_onexit
is a Microsoft extension. For ANSI portability, use atexit
. The _onexit_m
version of the function is for mixed mode use.
Requirements
Routine | Required header |
---|---|
_onexit |
<stdlib.h> |
For more compatibility information, see Compatibility.
Example
// crt_onexit.c
#include <stdlib.h>
#include <stdio.h>
/* Prototypes */
int fn1(void), fn2(void), fn3(void), fn4 (void);
int 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.
See also
Process and environment control
atexit
exit
, _Exit
, _exit
__dllonexit