Virtual Destructor Through a Base Pointer With a Live Count

1#include <iostream>
2using namespace std;
3 
4class A {
5public:
6    static int live;
7    A() { live++; cout << "A() live=" << live << endl; }
8    virtual ~A() { live--; cout << "~A() live=" << live << endl; }
9};
10int A::live = 0;
11 
12class B : public A {
13public:
14    B() { cout << "B()" << endl; }
15    ~B() { cout << "~B()" << endl; }
16};
17 
18class C : public B {
19public:
20    C() { cout << "C()" << endl; }
21    ~C() { cout << "~C()" << endl; }
22};
23 
24int main() {
25    A* p = new C;
26    B b;
27    cout << "live=" << A::live << endl;
28    delete p;
29    cout << "live=" << A::live << endl;
30    return 0;
31}