C++ IO流：标准输入输出流的重载

一、代码

#include <iostream>using namespace std;class Date{public:        Date(int year, int month , int day) : m_year(year), m_month(month), m_day(day) { }        //        friend ostream& operator<<(ostream& os, Date& dt);private:        int m_year, m_month, m_day;};//ostream& operator<<(ostream& os, Date& dt){        os<<dt.m_year<<"-"<<dt.m_month<<"-"<<dt.m_day<<endl;        return os;}int main(int argc, char*argv[]){        Date yesterday(2015, 4, 2), today(2015, 4, 3), tommorrow(2015, 4, 4);        cout<<yesterday<<today<<tommorrow;        return 0;}

二、输出结果