第十四周项目二-形状类族中的纯虚函数

来源：互联网发布：bytebuffer转byte数组编辑：程序博客网时间：2024/05/20 11:24

#include <iostream>using namespace std;class Shape{    public:    virtual float area()const=0;};class Circle:public Shape{    public:    Circle(float r=0);    virtual float area()const;    protected:    float radius;};Circle::Circle(float r){    radius=r;}float Circle::area()const{    return 3.141592*radius*radius;}class Rectangle:public Shape{    public:    Rectangle(float l,float w);    virtual float area()const;    protected:    float length;    float width;};Rectangle::Rectangle(float l,float w){    length=l;    width=w;}float Rectangle::area()const{    return length*width;}class Triangle:public Shape{    public:    Triangle(float ch,float h);    virtual float area()const;    protected:    float chang;    float high;};Triangle::Triangle(float ch,float h){    chang=ch;    high=h;}float Triangle::area()const{    return chang*high/2;}int main(){    Circle c1(12.6),c2(4.9);//建立Circle类对象c1,c2,参数为圆半径    Rectangle r1(4.5,8.4),r2(5.0,2.5);//建立Rectangle类对象r1,r2,参数为矩形长、宽    Triangle t1(4.5,8.4),t2(3.4,2.8); //建立Triangle类对象t1,t2，参数为三角形底边长与高    Shape *pt[6]= {&c1,&c2,&r1,&r2,&t1,&t2}; //定义基类指针数组pt，使它每一个元素指向一个派生类对象    double areas=0.0; //areas为总面积    for(int i=0; i<6; i++)    {        areas+=pt[i]->area();    }    cout<<"totol of all areas="<<areas<<endl;   //输出总面积    return 0;}

运行结果：

0 0