CODEWITHSUNDEEP
c++memoryscopeglobal-variables
Filip Mestanek
Filip Mestanek

Reputation: 97

C++ constructing global variable

i have a c++ code:

// includes, variables etc...
GraphStructure graphStructure;

void getInput() {
    graphStructure = GraphStructure(nodesCount, edgesCount);
    // HERE, the destructor is called!
    graphStructure.init(nodesCount, edgesCount);
    // Same code as constructor, but now its okay.
}

int main(int argc, char* argv[]) {
    getInput();
}

I would like to know, why the destructor of the object is called directly after its construction. Destructors are called after end of scope of a variable, which should be after the main function end.

Upvotes: 0

Views: 121

Answers (1)

David G
David G

Reputation: 96810

GraphStructure(nodesCount, edgesCount) is a temporary instance of GraphStructure. As such, its destructor is called when the full expression in which it is contained is evaluated (the end being at the semicolon ;).

If it were a local instance it would be bound by the scope of getInput(), not main(). Its destructor would get called when the compiler has reached the end of getInput() (just before the ending brace }). And the destructors of any local variables in main would get called when main finishes execution.

Upvotes: 3

Related Questions