Std::atexit (3) Linux Manual Page

std::atexit – std::atexit

Synopsis

Defined in header<cstdlib>

    int atexit(/*c-atexit-handler*/ *func);
(until C++ 11)

    int atexit(/*atexit-handler*/ *func);

int atexit(/*c-atexit-handler*/ *func) noexcept;
(1)(since C++ 11)

    int atexit(/*atexit-handler*/ *func) noexcept;

extern "C++" using /*atexit-handler*/ = void(); // exposition-only     (2)

extern "C" using /*c-atexit-handler*/ = void(); // exposition-only

Registers the function pointed to by func to be called on normal program termination (via std::exit() or returning from the main_function)
The functions will be called during the destruction of the static objects, in reverse order: if A was registered before B, then the call to B is made before the call to A. Same applies to the ordering between static object constructors and the calls to atexit: see std::exit (until C++11)
The functions may be called concurrently with the destruction of the objects with static storage duration and with each other, maintaining the guarantee that if registration of A was sequenced-before the registration of B, then the call to B is sequenced-before the call to A, same applies to the sequencing between static object constructors and calls to atexit: see std::exit (since C++11)
The same function may be registered more than once.
If a function exits via an exception, std::terminate is called.
atexit is thread-safe: 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.

Parameters

func – pointer to a function to be called on normal 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 <iostream>

#include <cstdlib>
void atexit_handler_1()

{
    std::cout << "at exit #1\n";
}
void atexit_handler_2()

{
    std::cout << "at exit #2\n";
}
int main()

{
    const int result_1 = std::atexit(atexit_handler_1);
    const int result_2 = std::atexit(atexit_handler_2);
    if ((result_1 != 0) or (result_2 != 0)) {
        std::cerr << "Registration failed\n";
        return EXIT_FAILURE;
    }
    std::cout << "returning from main\n";
    return EXIT_SUCCESS;
}

Output:

  returning from main
  at exit #2
  at exit #1

std::atexit (3) Linux Manual Page