流输入>>、流输出<<作为友元重载

流输入>>、流输出<< 作为友元重载

#include "stdafx.h"
#include <iostream>
using namespace std;

//流输入输出重载

class Complex
{
public:
	Complex(float x = 0, float y = 0)
		:_x(x), _y(y){}
	void dis()
	{
		cout << "(" << _x << "," << _y << ")" << endl;
	}

	//cout<<c<<c; 可以连续输入也就是将 第一次的结果返回并作为左边参数 
	//所以返回类型为ostream 而且对象没有消失所以为&
	//而参数 &c为输出内容不可更改加const
	friend ostream & operator<<(ostream &os, const Complex &c)
	{
		return os << "(" << c._x << "," << c._y << ")" << endl;

	}

	//因为是输入参数，所以可以更改参数&c 没有const
	friend istream & operator>>(istream &is,  Complex &c)
	{
		return is >> c._x >> c._y;
	}

private:
	float _x;
	float _y;
};


int _tmain(int argc, _TCHAR* argv[])
{
	Complex c(1, 2), c1(2, 3);
	//cin >> c;

	operator>>(cin, c);

	cout << c << c1 << endl;

	operator<<(operator<<(cout, c), c1) << endl;

	//a+b;  做成员 a.operator+(b)  cout.operator<<(c)
	//因为cout对象是标准库里面的 不能更改 所以不能做成员

	//      做友元 operator+(a,b) operator<<(cout,c)

	return 0;
}