C++输入输出运算符重载（“>>”“<<”）

源地址：http://blog.163.com/hbu_lijian/blog/static/126129153201211553330531/

//输入输出运算符只能用友元函数重载

#include <iostream>

#include <assert.h>

#include <string.h>

using namespace std;

class Complex

{

    double re,im;

public:

    Complex(double r,double i):re(r),im(i)

    {

    }

    Complex()

    {

        re = 0;

        im = 0;

    }

    Complex operator!();

    Complex operator+(const Complex &obj);

    //重载输入输出运算符，只能用友元函数

    friend ostream &operator<<(ostream &os,const Complex &c);// 注意friend后面没有" : "

    friend istream &operator>>(istream &is,Complex &c);

};

Complex Complex::operator +(const Complex &obj)

{

    Complex temp;

    temp.re = re + obj.re;

    temp.im = im + obj.im;

    return temp;

}

Complex Complex::operator !()

{

    Complex temp;

    temp.re = -re;

    temp.im = -im;

    return temp;

}

ostream & operator<<(ostream &os,const Complex &c)

{

    os << c.re;

    if(c.im > 0)

        os << "+" << c.im << "i" << endl;

    else

        os << c.im << "i" << endl;

    return os;

}

istream & operator>>(istream &is,Complex &c)

{

    is >> c.re >> c.im;

    return is;

}

int main(int argc,char *argv[])

{

    Complex obj1(1,2),obj2(3,4);

    Complex obj3 = obj1 + !obj2;

    cout << obj3;

    cin >> obj3;

    cout << obj3;

    return 0;

}