继承虚属性

虚函数的性质：

    无论虚函数被继承多少次，它仍然是虚函数；

    虚函数是分层的。

 

测试代码：

#include<iostream>
using namespace std;

class base
{
public:
 virtual void show(){cout<<"This is in base"<<endl;}
};

class derive1:public base
{
public:
 void show(){cout<<"This is in derive1"<<endl;}
};

class derive2:public derive1
{
public:
 void show(){cout<<"This is in derive2"<<endl;}
};

int main()
{
 base *p,a;
 derive1 b;
 derive2 c;

 p=&a;
 p->show();

 p=&b;
 p->show();

 p=&c;
 p->show();
 return 0;
}

测试结果：

This is in base
This is in derive1
This is in derive2
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