欢迎您访问程序员文章站本站旨在为大家提供分享程序员计算机编程知识!
您现在的位置是: 首页  >  IT编程

c++虚函数例子解析

程序员文章站 2024-01-01 10:16:58
#include using namespace std; class Shape { public: //普通函数前加virtual,普通函数变成了虚函数,=0表示抽象虚函数,子类必须实现该函数 virtual void printarea()=0; void hello() ......
#include <iostream>
using namespace std;
class shape
{
public:
//普通函数前加virtual,普通函数变成了虚函数,=0表示抽象虚函数,子类必须实现该函数 virtual void printarea()=0; void hello(){cout<<"shape hello function"<<endl;}; }; class circle:public shape { public: circle(int a):r(a){} void hello(){cout<<"circle hello function"<<endl;}; void printarea(){cout<<"圆形面积为:"<<r*r*3.14<<endl;} private: int r; }; class rectangle:public shape { public: rectangle(int a,int b):x(a),y(b){} void hello(){cout<<"rectangle hello function"<<endl;}; void printarea(){cout<<"矩形面积为:"<<x*y<<endl;} private: int x; int y; }; class square:public shape { public: square(int a):l(a){} void hello(){cout<<"square hello function"<<endl;}; void printarea(){cout<<"正方形面积为:"<<l*l<<endl;} private: int l; }; void prints(shape *s) {
  //基类指针s指向子类对象
//s调用的函数printarea是虚函数,所以会调用子类的printarea s->printarea();
//s调用的函数hello不是虚函数,所以只会调用基类的hello s->hello(); } int main() { circle a(1); prints(&a); square b(2); prints(&b); rectangle c(1,2); prints(&c); return 0; }

 

输出:

圆形面积为:3.14
shape hello function
正方形面积为:4
shape hello function
矩形面积为:2
shape hello function

 

上一篇:

下一篇: