利用友元函数实现对运算符的重载

/*
*Copyright (c) 2013 ,烟台大学计算机与控制工程学院
*All rights reserved.
*作者：王至超
*完成日期：2014年04月19
*版本号：v1.0
*问题描述：
*样例输入：
*样例输出：
*问题分析：用简单的方法，学会活学活用
*/
#include <iostream>
using namespace std;
class Complex
{
public:
Complex(){real=0;imag=0;}
Complex(double r,double i){real=r; imag=i;}
friend Complex operator+(Complex &c1,Complex &c2);
friend Complex operator-(Complex &c1,Complex &c2);
friend Complex operator*(Complex &c1,Complex &c2);
friend Complex operator/(Complex &c1,Complex &c2);
void display();
private:
double real;
double imag;
};
Complex operator+(Complex &c1,Complex &c2)
{
return Complex (c1.real+c2.real,c1.imag+c2.imag);
}
Complex operator-(Complex &c1,Complex &c2)
{
return Complex (c1.real-c2.real,c1.imag-c2.imag);
}
Complex operator*(Complex &c1,Complex &c2)
{
return Complex (c1.real*c2.real,c1.imag*c2.imag);
}
Complex operator/(Complex &c1,Complex &c2)
{
return Complex (c1.real/c2.real,c1.imag/c2.imag);
}
void Complex::display()
{
cout<<"("<<real<<","<<imag<<"i)"<<endl;
}
//下面定义用于测试的main()函数
int main()
{
Complex c1(3,4),c2(5,-10),c3;
cout<<"c1=";
c1.display();
cout<<"c2=";
c2.display();
c3=c1+c2;
cout<<"c1+c2=";
c3.display();
c3=c1-c2;
cout<<"c1-c2=";
c3.display();
c3=c1*c2;
cout<<"c1*c2=";
c3.display();
c3=c1/c2;
cout<<"c1/c2=";
c3.display();
return 0;
}