virtual C++ 多态

#include<iostream>using namespace std;class Class1{public :int no;virtual void print(){cout<<"Class1"<<endl;}};class Class2:public Class1{public:virtual void print(){cout<<"Class2"<<endl;}};class Class3:public Class1{public:virtual void print(){cout<<"Class3"<<endl;}};int main(){Class1 *p=new Class1();int n;while(n>=0){cin>>n;if(n%2==0)p=new Class2();else p=new Class3();p->print();}return 1;}