#include<iostream>
using namespace std;
class Base
{
public:
virtual void foo(){cout << 'a';}
};
class Middle:public Base
{
public:
void foo(){cout <<'b';}
};
class Derived:public Middle
{
public:
void foo(){cout <<'c';}
};
int main()
{
Base* p1;
Middle* p2;
Derived d;
p1 = &d;
p1->foo();
p2 = &d;
p2->foo();
} 程序运行结果为
