c++虚函数例子解析
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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