# std::at_quick_exit

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< cpp‎ | utility‎ | program

Defined in header `<cstdlib>` |  |
int at_quick_exit( /*atexit-handler*/* func ) noexcept; int at_quick_exit( /*c-atexit-handler*/* func ) noexcept; | (1) | (since C++11)
extern "C++" using /*atexit-handler*/ = void(); extern "C" using /*c-atexit-handler*/ = void(); | (2) | (exposition only*)

Registers the function pointed to by `func` to be called on quick program termination (via std::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, std::atexit must be used.

### Parameters

func | - | pointer to a function to be called on quick program termination

### Return value

​0​ if the registration succeeds, nonzero value otherwise.

### Notes

The two overloads are distinct because the types of the parameter `func` are distinct (language linkage is part of its type).

### Example

Run this code

    #include <cstdlib>
    #include <iostream>

    void f1()
    {
        std::cout << "pushed first" << std::endl; // flush is intentional
    }

    extern "C" void f2()
    {
        std::cout << "pushed second\n";
    }

    int main()
    {
        auto f3 = []
        {
            std::cout << "pushed third\n";
        };

        std::at_quick_exit(f1);
        std::at_quick_exit(f2);
        std::at_quick_exit(f3);
        std::quick_exit(0);
    }

Output:

    pushed third
    pushed second
    pushed first

### See also

abort | causes abnormal program termination (without cleaning up) (function)
exit | causes normal program termination with cleaning up (function)
atexit | registers a function to be called on std::exit() invocation (function)
quick_exit (C++11) | causes quick program termination without completely cleaning up (function)
C documentation for at_quick_exit

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