NAME¶

std::exit - std::exit

Synopsis¶

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) destructors of objects with static storage duration are called in
reverse order of completion of their constructors or the completion of
their dynamic initialization, and the functions passed to std::atexit
are called in reverse order they are registered (last one first).
a) any static objects whose initialization was completed before the
call to std::atexit for some function F will be destroyed after the (until C++11)
call to F during program termination.
b) any static objects whose construction began after the call to
std::atexit for some function F will be destroyed before the call to F
during program termination (this includes the case where std::atexit
was called from the constructor of the static object)
1) The destructors of objects with thread local storage duration that
are associated with the current thread, the destructors of objects
with static storage duration, and the functions registered with
std::atexit are executed concurrently, while maintaining the following
guarantees:
a) The last destructor for thread-local objects is sequenced-before
the first destructor for a static object
b) If the completion of the constructor or dynamic 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 (since C++11)
c) If the completion of the initialization of a static object A was
sequenced-before the call to std::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 to std::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 to std::atexit for some function F1 was sequenced-before
the call to std::atexit for some function F2, then the call to F2
during termination is sequenced-before the call to F1

* In the above,

* if any function registered with atexit or any destructor
of static/thread-local object throws an exception,
std::terminate is called
* if the compiler opted to lift dynamic initialization of an
object to the static initialization phase of non-local
initialization, the sequencing of destruction honors its
would-be dynamic initialization.
* If a function-local (block-scope) static object was
destroyed and then that function is called from the
destructor of another static object and the control flow
passes through the definition of that object (or if it is
used indirectly, via pointer or reference), the behavior
is undefined.
* if a function-local (block-scope) static object was
initialized during construction of a subobject of a class
or array, it is only destroyed after all subobjects of
that class or all elements of that array were destroyed.

2) all C streams are flushed and closed
3) files created by std::tmpfile are removed
4) control is returned to the host environment. If exit_code is 0 or EXIT_SUCCESS,
an implementation-defined status indicating successful termination is returned. If
exit_code is EXIT_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 automatic storage duration are
not called.

Relationship with the main function¶

Returning from the main function, either by a return statement or by reaching the
end of the function performs the normal function termination (calls the destructors
of the variables with automatic storage durations) and then executes std::exit,
passing the argument of the return statement (or 0 if implicit return was
used) as exit_code.

Parameters¶

exit_code - exit status of the program

Return value¶

(none)

Example¶

// Run this code

#include <iostream>
#include <cstdlib>

struct Static {
~Static()
{
std::cout << "Static dtor\n";
}
};

struct Local {
~Local()
{
std::cout << "Local dtor\n";
}
};

Static static_variable; // dtor of this object *will* be called

void atexit_handler()
{
std::cout << "atexit handler\n";
}

int main()
{
Local local_variable; // dtor of this object will *not* be called
const int result = std::atexit(atexit_handler); // handler will be called

if (result != 0) {
std::cerr << "atexit registration failed\n";
return EXIT_FAILURE;
}

std::cout << "test\n";
std::exit(EXIT_FAILURE);

std::cout << "this line will *not* be executed\n";
}

Output:¶

test
atexit handler
Static dtor

See also¶

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