std::atexit (3) - Linux Manuals

std::atexit: std::atexit

NAME

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