Counting instances of individual derived classes

Question

I\'d like to be able to count instances of classes that belong in the same class hierarchy.

For example, let\'s say I have this:

class A;
class B: pu         


        

Answer 1

Use a static member variable for each class.

struct A {
    A() { mInstances++; }
    ~A() { mInstances--; }
    static size_t mInstances;
    static size_t GetInstancesCount() { return mInstances; }
};

size_t A::mInstances;

int main() {
    A* a = new A;
    A* aa = new A;
    cout << A::GetInstancesCount() << endl;
    delete a;
    delete aa;
    cout << A::GetInstancesCount() << endl;
    return 0;
}