/*
* Copyright (c) 2014, 烟台大学计算机学院
* All rights reserved.
* 作 者:纪丽娜
* 完成日期:2014 年05月25日
* 版 本 号:v1.0
* 问题描述:
* 在项目1的基础上,
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
{
public:
Point(double a=0,double b=0 ):x(a),y(b){} //构造函数
double distance(const Point &p) const; //求距离
friend ostream & operator<<(ostream &,const Point &);//重载运算符“<<”
protected: //受保护成员
double x,y;
};
double Point::distance(const Point &p) const //求距离
{
double dx = x-p.x;
double dy = y-p.y;
return sqrt(dx*dx+dy*dy);
}
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 a=0,double b=0,double r=0):Point(a,b),radius(r){ } //构造函数
double area ( ) const; //计算圆面积
friend ostream &operator<<(ostream &,const Circle &);//重载运算符“<<”
friend int locate(const Point &p, const Circle &c); //判断点p在圆上、圆内或圆外,返回值:<0圆内,==0圆上,>0 圆外
//重载关系运算符(种)运算符,使之能够按圆的面积比较两个圆的大小;
bool operator>(const Circle &);
bool operator<(const Circle &);
bool operator>=(const Circle &);
bool operator<=(const Circle &);
bool operator==(const Circle &);
bool operator!=(const Circle &);
protected:
double 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<<endl;
return output;
}
//判断点p在圆内、圆c内或圆c外
int locate(const Point &p, const Circle &c)
{
double ds;
Point p2(c.x,c.y);
ds=p2.distance(p)-c.radius;
if(ds==0)
{
return 0;
}
else if(ds<0)
{
return -1;
}
else
{
return 1;
}
}
//重载关系运算符(种)运算符,使之能够按圆的面积比较两个圆的大小;
bool Circle::operator>(const Circle &c)
{
return (this->radius - c.radius) > 0;
}
bool Circle::operator<(const Circle &c)
{
return (c.radius - this->radius) > 0;
}
bool Circle::operator>=(const Circle &c)
{
return !(*this < c);
}
bool Circle::operator<=(const Circle &c)
{
return !(*this > c);
}
bool Circle::operator==(const Circle &c)
{
return (this->radius-c.radius)==0;
}
bool Circle::operator!=(const Circle &c)
{
return !(*this==c);
}
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;
cout<<endl;
cout<<"圆c1: "<<c1;
cout<<"圆c2: "<<c2<<endl;
cout<<"c1与c2的关系是:\n";
if(c1>c2) cout<<"大于"<<endl;
if(c1<c2) cout<<"小于"<<endl;
if(c1>=c2) cout<<"大于等于"<<endl;
if(c1<=c2) cout<<"小于等于"<<endl;
if(c1==c2) cout<<"等于"<<endl;
if(c1!=c2) cout<<"不等于"<<endl;
return 0;
}
第十三周项目二圆的比较
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