用类的友元函数完成运算符的重载

/* 

* 程序的版权和版本声明部分 

* Copyright (c)2012, 烟台大学计算机学院学生 

* All rightsreserved. 

* 文件名称： object.cpp 

* 作者：刘清远

* 完成日期： 2013年 4 月 22 日 

* 版本号： v1.0 

* 输入描述：无

 * 问题描述： 

* 程序输出： 

*/  

#include <iostream>
using namespace std;
class Complex
{public:
Complex(){real=0;imag=0;}
Complex(double r,double i){real=r;imag=i;}
Complex operator+(Complex &c2);
Complex operator-(Complex &c2);
Complex operator*(Complex &c2);
Complex operator/(Complex &c2);
void display();
private:
double real;
double imag;
};
Complex Complex::operator +(Complex&c2) 
{
 return Complex(real+c2.real,imag+c2.imag);
}
Complex Complex::operator-(Complex&c2)
{
 return Complex(real-c2.real,imag-c2.imag);
}
Complex Complex::operator *(Complex&c2)
{
 return Complex(real*c2.real+imag*c2.imag,real*c2.imag+imag*c2.real);
}
Complex Complex::operator /(Complex&c2)
{
 return Complex((real*c2.real+imag*c2.imag)/(c2.real*c2.real+c2.imag*c2.imag),(imag*c2.real-real*c2.imag)/(c2.real*c2.real+c2.imag*c2.imag));  
}
void Complex::display()
{
cout<<"("<<real<<","<<imag<<"i)"<<endl;
}
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();
 system ("pause");
 return 0;
}