8-2 友元函数

/** 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： x.cpp* 作者：王心垚* 完成日期： 2013年 4 月24  日* 版本号： v1.0* 输入描述：* 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;}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,c2.imag-c2.imag);}Complex operator*(Complex &c1,Complex &c2){   Complex c;   c.real=c1.real*c2.real-c1.imag*c2.imag;   c.imag=c1.imag*c2.real+c1.imag*c2.imag;   return c;}Complex operator/(Complex &c1,Complex &c2){    Complex c;    c.real=(c1.real*c2.real+c1.imag*c2.imag)/(c2.real*c2.real+c2.imag*c2.imag);    c.imag=(c1.imag*c2.real-c1.real*c2.imag)/(c2.real*c2.real+c2.imag*c2.imag);    return c;}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();int aa;cin>>aa;return 0;}