Reputation: 2143

Some explanation required regarding the scope of my variable

/* simple class that has a vector of ints within it */
class A
{
public:
   vector<int> int_list;
};

/* some function that just returns an int, defined elsewhere */
int foo();

/* I want to fill the object's int_list up */
A a_obj;

int main() {
   for (int i = 0; i < 10; i++) {
      int num = foo();
      a_obj.int_list.push_back( num );
   }
}

Is the scope of num limited to the for loop? Will it be destroyed once the for loop is exited? If I try to access the numbers in a_obj's int_list will I not be able to as the numbers inside will have been destroyed?

Upvotes: 1

Answers (4)

cpx

Reputation: 17577

Is the scope of num limited to the for loop? Will it be destroyed once the for loop is exited?

Yes, because num is local to for-loop.

If I try to access the numbers in a_obj's int_list will I not be able to as the numbers inside will have been destroyed?

No, the numbers inside list won't be destroyed when it exits the for-loop because you're copying the numbers to the list and A a_obj; is declared in global scope which means it gets destroyed at the end of your program.

Upvotes: 1

Pepe

Reputation: 405

yea, each time the for loop iterates it creates a new instance of num on the stack. but you are passing the value of num into int_list where it will be stored until a_obj goes out of scope

Upvotes: 0