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Defined in header <cstdlib> | ||
void exit(int exit_code); | (until C++11) | |
[[noreturn]]void exit(int exit_code); | (since C++11) | |
Causes normal program termination to occur.
Several cleanup steps are performed:
1) Objects with static storage duration are destroyed and functions registered by callingstd::atexit are called: a) Non-local objects with static storage duration are destroyed in the reverse order of the completion of their constructor. b) Functions registered withstd::atexit are called in the reverse order of their registration, except that a function is called after any previously registered functions that had already been called at the time it was registered. c) For each functionf registered withstd::atexit and each non-local objectobj of static storage duration,
d) For each local objectobj with static storage duration,obj is destroyed as if a function calling the destructor ofobj were registered withstd::atexit at the completion of the constructor ofobj. | (until C++11) |
1) The destructors of objects with thread localstorage duration that are associated with the current thread, the destructors of objects with static storage duration, and the functions registered withstd::atexit are executed concurrently, while maintaining the following guarantees: a) The last destructor for thread-local objects issequenced-before the first destructor for a static object. b) If the completion of the constructor ordynamic initialization for thread-local or static object A was sequenced-before thread-local or static object B, the completion of the destruction of B is sequenced-before the start of the destruction of A. c) If the completion of the initialization of a static object A was sequenced-before the call tostd::atexit for some function F, the call to F during termination is sequenced-before the start of the destruction of A. d) If the call tostd::atexit for some function F was sequenced-before the completion of initialization of a static object A, the start of the destruction of A is sequenced-before the call to F during termination. e) If a call tostd::atexit for some function F1 was sequenced-before the call tostd::atexit for some function F2, then the call to F2 during termination is sequenced-before the call to F1. | (since C++11) |
atexit or any destructor of static/thread-local object throws an exception,std::terminate is called.exit_code is0 orEXIT_SUCCESS, an implementation-defined status indicating successful termination is returned. Ifexit_code isEXIT_FAILURE, an implementation-defined status indicating unsuccessful termination is returned. In other cases implementation-defined status value is returned.Stack is not unwound: destructors of variables with automaticstorage duration are not called.
Contents |
Returning from themain function, either by areturn statement or by reaching the end of the function performs the normal function termination (calls the destructors of the variables with automaticstorage durations) and then executesstd::exit, passing the argument of the return statement (or0 if implicit return was used) asexit_code.
| exit_code | - | exit status of the program |
(none)
#include <cstdlib>#include <iostream> struct Static{ ~Static(){std::cout<<"Static destructor\n";}}; struct Local{ ~Local(){std::cout<<"Local destructor\n";}}; Static static_variable;// Destructor of this object *will* be called void atexit_handler(){std::cout<<"atexit handler\n";} int main(){ Local local_variable;// Destructor of this object will *not* be calledconstint result=std::atexit(atexit_handler);// Handler will be called if(result!=0){std::cerr<<"atexit registration failed\n";returnEXIT_FAILURE;} std::cout<<"test\n"; std::exit(EXIT_FAILURE); std::cout<<"this line will *not* be executed\n";}
Output:
testatexit handlerStatic destructor
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
| DR | Applied to | Behavior as published | Correct behavior |
|---|---|---|---|
| LWG 3 | C++98 | during cleanup, the behavior was unclear when (1) a function is registered withstd::atexit or (2) a static local object is initialized | made clear |
| causes abnormal program termination (without cleaning up) (function)[edit] | |
| registers a function to be called onstd::exit() invocation (function)[edit] | |
(C++11) | causes quick program termination without completely cleaning up (function)[edit] |
(C++11) | registers a function to be called onstd::quick_exit invocation (function)[edit] |
C documentation forexit | |
