quick_exit for Normal Program Termination without Completely Cleaning Up

Defined in header <stdlib.h>.

_Noreturn void quick_exit( int exit_code ); // since C11 and until C23
[[noreturn]] void quick_exit( int exit_code ); // since C23

Causes normal program termination to occur without completely cleaning the resources.

Functions passed to at_quick_exit are called in reverse order of their registration. After calling the registered functions, calls _Exit(exit_code).

Functions passed to atexit or signal handlers passed to signal are not called.

Example

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

void f1(void)
{
    puts("pushed first");
    fflush(stdout);
}

void f2(void)
{
    puts("pushed second");
}

void f3(void)
{
    puts("won't be called");
}

int main(void)
{
    at_quick_exit(f1);
    at_quick_exit(f2);
    atexit(f3);
    quick_exit(0);
}

Function at_quick_exit()

Defined in header <stdlib.h>

int at_quick_exit( void (*func)(void) ); // since C11

Registers the function pointed to by func to be called on quick program termination (via quick_exit).

Calling the function from several threads does not induce a data race. The implementation is guaranteed to support the registration of at least 32 functions. The exact limit is implementation-defined.

The registered functions will not be called on normal program termination. If a function need to be called in that case, atexit must be used.

Return Value

0​ if the registration succeeds, nonzero value otherwise.

Example

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

void f1(void)
{
    puts("pushed first");
    fflush(stdout);
}

void f2(void)
{
    puts("pushed second");
}

int main(void)
{
    at_quick_exit(f1);
    at_quick_exit(f2);
    quick_exit(0);
}

[...]