#include <iostream>

using std::cout;
using std::endl;

struct X     { X() { cout << "X::X()" << endl; }  virtual ~X() { cout << "X::~X()" << endl; } };
struct Y : X { Y() { cout << "Y::Y()" << endl; }  virtual ~Y() { cout << "Y::~Y()" << endl; } };

int main()
{
	Y* y = new Y;
	delete y;
	cout << endl;

	// Ohne virtual X::~X Verhalten undefiniert
	X* x = new Y;
	delete x;
}