#include <iostream>
#include <cstdlib>
using namespace std;

/**
 * base class A with virtual destructor
 */
class A {
public:
	virtual ~A() { }
};

/**
 * class B is a A
 */
class B : public A {
};

/**
 * class C is a B
 */

class C : public B {
};

/**
 * main
 */
int main() {
	A *a = new A;
	A *b = new B;
	A *c = new C;
	
	// ok, c is of class C that inherits of B
	B *p = dynamic_cast<B *>(c);
	
	// not ok ! will return NULL
	B *q = dynamic_cast<B *>(a);
	
	cout << "p = " << p << endl;
	cout << "q = " << q << endl;
	
	return EXIT_SUCCESS;
}