关于虚函数的一个小例子

虚函数的提出其实和C++的多态有着莫大的关系，先看一个例子;

#include <iostream>
using namespace std;
class A
{
public:
    void print()
    //virtual void print()

    {
        cout<<"This is A"<<endl;
    }
};

class B:public A
{
public:
    void print(){cout<<"This is B"<<endl;}

};

int main(){

    A a;

    B b;

    a.print();
    b.print();

    A* p1=&a;

    A* p2=&b;

    p1->print();

    p2->print();

}


从结果可以看到:
This is A
This is B
This is A
This is A
将父类的print函数改为虚函数，也是将void print()改为virtual void print(),则结果就不同了:
This is A
This is B
This is A
This is B