//8_3.cpp
#include<iostream>
using namespace std;
class complex	//復數類聲明
{
public:	//外部接口
	complex(double r=0.0,double i=0.0){real=r;imag=i;}	//構造函數
	friend complex operator + (complex c1,complex c2);	//運算符+重載友元函數
	friend complex operator - (complex c1,complex c2);	//運算符-重載友元函數
	void display();	//顯示復數的值
private:	//私有數據成員
	double real;
	double imag;
};			//顯示函數實現
void complex::display()
{	cout<<"("<<real<<","<<imag<<")"<<endl;}
complex operator +(complex c1,complex c2)	//運算符重載友元函數實現
{	return complex(c2.real+c1.real,c2.imag+c1.imag);}
complex operator -(complex c1,complex c2)	//運算符重載友元函數實現
{	return complex(c1.real-c2.real,c1.imag-c2.imag);}
void main()	//主函數
{
	complex c1(5,4),c2(2,10),c3;
	cout<<"c1=";c1.display();
	cout<<"c2=";c2.display();
	c3=c1-c2;	//使用重載運算符
	cout<<"c3=c1-c2=";
	c3.display();
	c3=c1+c2;	//使用重載運算符
	cout<<"c3=c1+c2=";
	c3.display();
}