MOOC清华《面向对象程序设计》第4章：虚函数实验

#include <iostream>using namespace std;class Base{public:virtual void print(){cout << "Base::print()" << endl;}};class Derive:public Base{public:void print(){cout << "Derive::print()" << endl;}};void fun(Base& obj){obj.print();}int main(){Derive d;d.print();fun(d);return 0;}

两个要点：第一，函数前加虚函数标识符virtual； 第二，对象类型变成引用&。