问题
I wonder that can sure order between destruction of global object and atexit
in C++
I have a global object and register atexit
function like below:
static MyClass g_class;
void onExit()
{
// do some destruction
}
int main()
{
atexit(onExit);
return 0;
}
I've found onExit()
is invoked before MyClass::~MyClass()
in Visual Studio 2012 and gcc4.7.2. Am I sure that onExit
is always invoked before global object(like g_class
) destruction?
I wonder global object register order and atexit
register order use same order table.
Or there is no relation between global object order and atexit
order?
Edited : Sorry I wrote a mistake. I'm so confused while tidying example code. onExit()
is invoked before ~MyClass().
回答1:
UPDATE: The OP made some confusion, and it seems VC11 does indeed behave as specified by the C++11 Standard. The following answer was written in the assumption that it did not.
Therefore, the answer to this question:
Am I sure that
onExit
is always invoked before global object(likeg_class
) destruction?
Is "Yes", as long as you are working with a fully-compliant compiler.
I've found
MyClass::~MyClass()
is invoked beforeonExit()
in Visual Studio 2012.
If this is the case, then it is a bug in VC11. Per Paragraph 3.6.3/1 of the C++11 Standard:
Destructors (12.4) for initialized objects (that is, objects whose lifetime (3.8) has begun) with static storage duration are called as a result of returning from
main
and as a result of callingstd::exit
(18.5). [...]
Also, per Paragraph 3.6.3/3:
If the completion of the initialization of an object with static storage duration is sequenced before a call to
std::atexit
(see<cstdlib>
, 18.5), the call to the function passed tostd::atexit
is sequenced before the call to the destructor for the object.
Therefore, in your case, onexit()
should be invoked before the destructor of MyClass
.
As far as I can tell, Clang 3.2 and GCC 4.8.0 are compliant in this respect, as shown in this live example.
来源:https://stackoverflow.com/questions/16010083/order-between-destruction-of-global-object-and-atexit-in-c