程序代码：

#include "stdafx.h"
#include <iostream>

class A
{
public:
    A() {}
    virtual ~A() {}

public:
    virtual void Display() { std::cout << "A" << std::endl; }
};

class B : public A
{
public:
    B() : A() {}
    virtual ~B() {}

public:
    virtual void Display() { std::cout << "B" << std::endl; }
};

int main()
{
    B* b = new B();
    b->Display();

    UINT32 p = (UINT32)b;
    A* a = (A*)p;
    a->Display();

    char ch;
    std::cin >> ch;
}