C++虚函数、赋值兼容原则

#include <iostream.h>

class A
{
public:
    void f1()
    { cout << "a" << endl; }
    virtual void f2()
    { cout << "b" << endl; }
};

class B : public A
{
public:
    void f1()
    { cout << "c" << endl; }
    virtual void f2()
    { cout << "d" << endl; }
};

void main()
{
    A a;
    B b;
    a.f1();
    a.f2();
    b.f1();
    cout << "--------------------" << endl;

    A *pa = &b;
    pa->f1();//a
    pa->f2();//d
    cout << "-------------------" << endl;

    A *fa = (A *)&b;
    fa->f1();//a
    fa->f2();//d
    cout << "-------------------" << endl;
}