/*
*Copyright (c) 2013 ,煙臺大學計算機學院
*All rights reserved.
*作者：張鳳寧
*完成日期：2014年4月16
*版本號：v1.0
*問題描述：
*樣例輸入：
*樣例輸出：
*問題分析：用簡單的方法，學會活學活用
*/
#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 &, Complex &);
    friend Complex operator-(Complex &, Complex &);
    friend Complex operator*(Complex &, Complex &);
    friend Complex operator/(Complex &, Complex &);
    friend void display(Complex &);
private:
    double real;
    double imag;
};
//下面定義成員函式
Complex::Complex operator+(Complex &a, Complex &b)
{
    Complex c;
    c.real=a.real+b.real;
    c.imag=a.imag+b.imag;
    return c;
}
Complex::Complex operator-(Complex &a, Complex &b)
{
    Complex c;
    c.real=a.real-b.real;
    c.imag=a.imag-b.imag;
    return c;
}
Complex::Complex operator*(Complex &a, Complex &b)
{
    Complex c;
    c.real=a.real*b.real;
    c.imag=a.imag*b.imag;
    return c;
}
Complex::Complex operator/(Complex &a, Complex &b)
{
    Complex c;
    c.real=a.real/b.real;
    c.imag=a.imag/b.imag;
    return c;
}
void display(Complex &s)
{
    cout<<"("<<s.real<<","<<s.imag<<")"<<endl;
}
//下面定義用於測試的main()函式
int main()
{
    Complex c1(3,4),c2(5,-10),c3;
    cout<<"c1=";
    display(c1);
    cout<<"c2=";
    display(c2);
    c3=c1+c2;
    cout<<"c1+c2=";
    display(c3);
    c3=c1-c2;
    cout<<"c1-c2=";
    display(c3);
    c3=c1*c2;
    cout<<"c1*c2=";
    display(c3);
    c3=c1/c2;
    cout<<"c1/c2=";
    display(c3);
    return 0;
}
執行結果：
 

心得體會：友元有段時間有點不熟。