Defined in header <cstdlib> | ||
|---|---|---|
| (1) | ||
int atexit( /*c-atexit-handler*/* func ); int atexit( /*atexit-handler*/* func ); | (until C++11) | |
int atexit( /*c-atexit-handler*/* func ) noexcept; int atexit( /*atexit-handler*/* func ) noexcept; | (since C++11) | |
extern "C++" using /*atexit-handler*/ = void(); // exposition-only extern "C" using /*c-atexit-handler*/ = void(); // exposition-only | (2) |
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 | (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 | (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.
| func | - | pointer to a function to be called on normal program termination |
0 if the registration succeeds, nonzero value otherwise.
The two overloads are distinct because the types of the parameter func are distinct (language linkage is part of its type).
#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
| causes abnormal program termination (without cleaning up) (function) |
|
| causes normal program termination with cleaning up (function) |
|
|
(C++11) | causes quick program termination without completely cleaning up (function) |
|
(C++11) | registers a function to be called on quick_exit invocation (function) |
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