第十一周项目4 - 类族的设计

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问题及代码：/* *Copyright (c) 2015,烟台大学计算机学院*All rights reserved.*文件名称：test.cop*作者：*完成日期：2015年5月24日*版本号：v1.0**问题描述： *输入描述：*输出描述：

#include <iostream>using namespace std;class Point{public:Point(double x=0,double y=0); //构造函数void setPoint(double,double);                  //设置坐标值double getX( ) const {return x;}              //读x坐标double getY( ) const {return y;}              //读y坐标friend ostream & operator<<(ostream &,const Point &);//重载运算符“<<”protected: //受保护成员double x,y;};//Point的构造函数Point::Point(double a,double b){x=a;y=b;}//设置x和y的坐标值void Point::setPoint(double a,double b){x=a;y=b;}ostream & operator<<(ostream &output,const Point &p){output<<"["<<p.x<<","<<p.y<<"]"<<endl;return output;}class Circle:public Point   //circle是Point类的公用派生类{public:Circle(double x=0,double y=0,double r=0);  //构造函数void setRadius(double);                  //设置半径值double getRadius( ) const;               //读取半径值double area ( ) const;                   //计算圆面积friend ostream &operator<<(ostream &,const Circle &);//重载运算符“<<”protected:double radius;};//定义构造函数，对圆心坐标和半径初始化Circle::Circle(double a,double b,double r):Point(a,b),radius(r){ }//设置半径值void Circle::setRadius(double r){radius=r;}//读取半径值double Circle::getRadius( ) const{return radius;}//计算圆面积double Circle::area( ) const{return 3.14159*radius*radius;}//重载运算符“<<”，使之按规定的形式输出圆的信息ostream &operator<<(ostream &output,const Circle &c){output<<"Center=["<<c.x<<", "<<c.y<<"], r="<<c.radius<<", area="<<c.area( )<<endl;return output;}int main( ){Circle c(3.5,6.4,5.2);cout<<"original circle:\nx="<<c.getX()<<", y="<<c.getY()<<", r="<<c.getRadius( ) <<", area="<<c.area( )<<endl;c.setPoint(5,5);cout<<"new circle:\n"<<c;return 0;}

运行结果：

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