/*
 * Copyright (c) 2014, 煙臺大學計算機學院
 * All rights reserved.
 * 作    者：紀麗娜
 * 完成日期：2014 年05月25日
 * 版 本 號：v1.0
 * 問題描述：
 * 在專案1的基礎上，
   在圓類上過載關係運算符（6種），
   使之能夠按圓的面積比較兩個圓的大小。
   自編main函式完成測試。
*/
#include <iostream>
#include<Cmath>
using namespace std;
class Point
{
public:
	Point(double a=0,double b=0 ):x(a),y(b){}	//建構函式
	double distance(const Point &p) const;	//求距離

	friend ostream & operator<<(ostream &,const Point &);//過載運算子“<<”
protected:										 //受保護成員
	double x,y;
};




double Point::distance(const Point &p) const	//求距離
{
	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類的公用派生類
{
public:
	Circle(double a=0,double b=0,double r=0):Point(a,b),radius(r){ } //建構函式
	double area ( ) const; //計算圓面積
	friend ostream &operator<<(ostream &,const Circle &);//過載運算子“<<”
	friend int locate(const Point &p, const Circle &c); //判斷點p在圓上、圓內或圓外，返回值：<0圓內，==0圓上，>0 圓外
	//過載關係運算符（種）運算子，使之能夠按圓的面積比較兩個圓的大小；
	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;
};


//計算圓面積
double Circle::area( ) const
{
	return 3.14159*radius*radius;
}

//過載運算子“<<”，使之按規定的形式輸出圓的資訊
ostream &operator<<(ostream &output,const Circle &c)
{
	output<<"Center=["<<c.x<<", "<<c.y<<"], r="<<c.radius<<endl;
	return output;
}

//判斷點p在圓內、圓c內或圓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;
    }
}

//過載關係運算符（種）運算子，使之能夠按圓的面積比較兩個圓的大小；
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應該大於c1
	Point p1(1,1),p2(3,-2),p3(7,3);  //分別位於c1內、上、外

	cout<<"圓c1: "<<c1;
	cout<<"點p1: "<<p1;
	cout<<"點p1在圓c1之"<<((locate(p1, c1)>0)?"外":((locate(p1, c1)<0)?"內":"上"))<<endl;
	cout<<"點p2: "<<p2;
	cout<<"點p2在圓c1之"<<((locate(p2, c1)>0)?"外":((locate(p2, c1)<0)?"內":"上"))<<endl;
	cout<<"點p3: "<<p3;
	cout<<"點p3在圓c1之"<<((locate(p3, c1)>0)?"外":((locate(p3, c1)<0)?"內":"上"))<<endl;
	cout<<endl;

	cout<<"圓c1: "<<c1;
	cout<<"圓c2: "<<c2<<endl;
	cout<<"c1與c2的關係是：\n";
	if(c1>c2) cout<<"大於"<<endl;
	if(c1<c2) cout<<"小於"<<endl;
	if(c1>=c2) cout<<"大於等於"<<endl;
	if(c1<=c2) cout<<"小於等於"<<endl;
	if(c1==c2) cout<<"等於"<<endl;
	if(c1!=c2) cout<<"不等於"<<endl;

	return 0;
}