13.2圆的比较

/** 程序的版权和版本声明部分* Copyright (c)2014, 烟台大学计算机学院学生* All rightsreserved.* 文件名称：a.cpp* 作    者：孔云* 完成日期：2014年5月25日* 版 本 号： v1.0* 输入描述：主函数已给出。* 问题描述：（1）先建立一个Point(点)类，包含数据成员x,y(坐标点)；            （2）以Point为基类，派生出一个Circle(圆)类，增加数据成员(半径)，基类的成员表示圆心；            （3）编写上述两类中的构造、析构函数及必要运算符重载函数（本项目主要是输入输出）；            （4）定义友元函数int locate，判断点p与圆的位置关系（返回值<0圆内，==0圆上，>0 圆外）；            （5）在圆类上重载关系运算符（6种），使之能够按圆的面积比较两个圆的大小。自编main函数完成测试。*/#include <iostream>#include <Cmath>using namespace std;class Point{private:    double x,y;public:    Point():x(0),y(0) {}//构造函数    Point(double,double);//赋值函数    double getx();//接口函数    double gety();    friend ostream&operator<<(ostream&,Point&);//输出运算符重载函数    double distance(Point&);//两点之间的距离    ~Point();//析构函数};Point::Point(double a,double b){    x=a;    y=b;}double Point::getx(){    return x;}double Point::gety(){    return y;}double Point::distance(Point& p){    double dx=p.getx()-getx();    double dy=p.gety()-gety();    return sqrt(dx*dx+dy*dy);}ostream&operator<<(ostream& out,Point& c){    out<<"("<<c.getx()<<","<<c.gety()<<")"<<endl;    return out;}Point::~Point() {}class Circle:public Point{protected:    double r;public:    Circle():Point(),r(0) {}    Circle(double,double,double);    ~Circle();    double area();    friend int locate(Point&,Circle&);//判断点与圆的位置关系    //声明六种关系运算符重载    bool operator<(Circle&);    bool operator>(Circle&);    bool operator==(Circle&);    bool operator!=(Circle&);    bool operator<=(Circle&);    bool operator>=(Circle&);    friend ostream&operator<<(ostream&,Circle&);//输出运算符重载};Circle::Circle(double a,double b,double c):Point(a,b),r(c) {}Circle::~Circle() {}int locate(Point& f,Circle& g){    Point l(g.getx(),g.gety());    double d=l.distance(f);    if(d>g.r)        return 1;    else if(d<g.r)        return -1;    else        return 0;}double Circle::area()//求圆的面积{    double pi=3.1415926;    return 2*pi*r*r;}//定义六种关系运算符重载bool Circle::operator<(Circle& c){    if(area()<c.area())        return true;    else        return false;}bool Circle::operator>(Circle& c){    if(area()>c.area())        return true;    else        return false;}bool Circle::operator==(Circle& c){    if(area()==c.area())        return true;    else        return false;}bool Circle::operator!=(Circle& c){    if(area()==c.area()) return false;    return true;}bool Circle::operator<=(Circle& c){    if(area()>c.area()) return false;    return true;}bool Circle::operator>=(Circle& c){    if(area()<c.area()) return false;    return true;}ostream&operator<<(ostream& out,Circle& k){    out<<"圆心：("<<k.getx()<<","<<k.gety()<<"),半径"<<k.r<<endl;    return out;}int main(){    Circle c1(3,2,4),c2(4,5,5);      //c2应该大于c1    Point p1(1,1),p2(3,-2),p3(7,3);  //分别位于c1内、上、外    cout<<"圆c1: "<<c1;    cout<<"点p1: "<<p1;    cout<<"点p1在圆c1之"<<((locate(p1, c1)>0)?"外":((locate(p1, c1)<0)?"内":"上"))<<endl;    cout<<"点p2: "<<p2;    cout<<"点p2在圆c1之"<<((locate(p2, c1)>0)?"外":((locate(p2, c1)<0)?"内":"上"))<<endl;    cout<<"点p3: "<<p3;    cout<<"点p3在圆c1之"<<((locate(p3, c1)>0)?"外":((locate(p3, c1)<0)?"内":"上"))<<endl;    if(c1>c2)        cout<<"c1大于c2"<<endl;    if(c1<c2)        cout<<"c1小于c2"<<endl;    if(c1==c2)        cout<<"c1等于c2"<<endl;    if(c1!=c2)        cout<<"c1不等于c2"<<endl;    if(c1>=c2)        cout<<"c1大于等于c2"<<endl;    if(c1<=c2)        cout<<"c1小于等于c2"<<endl;    return 0;}

心得体会：为什么不给力？“* 上传图片失败！”真讨厌！不过还好，重要的是知道：有了结实的地基，建起的高楼大厦才会牢固。