改了很久，还是感觉怪怪的

#include <iostream>
using namespace std;

class DayOfYear
{
public:
    friend bool equal(DayOfYear date1,DayOfYear date2);    //友元
    DayOfYear(int the_month,int the_day);
    DayOfYear(){}
    void input();
    void output();
    int get_month();
    int get_day();
//private:
    void check_date();
    int month;
    int day;
};

int main ()
{
    DayOfYear today,bach_birthday(3,21);

    cout<<"输入今天日期：";
    today.input();
    cout<<"今天是";
    today.output();

    cout<<"xxx的生日是";
    bach_birthday.output();

    if(equal(today,bach_birthday))
        cout<<"happy!";
    else
        cout<<"unhappy!";

    return 0;
}

bool equal(DayOfYear date1,DayOfYear date2)
{
    return(date1.month == date2.month && date1.day ==date2.day);
}

DayOfYear::DayOfYear(int the_month,int the_day):month(the_month),day(the_day)
{
    //无动作
}
int DayOfYear::get_month()
{
    return month;
}
int DayOfYear::get_day()
{
    return day;
}
//使用iostream
void DayOfYear::input()
{
    cout<<"输入月份：";
    cin>>month;
    cout<<"输入日期:";
    cin>>day;
}
void DayOfYear::output()
{
    cout<<"月:"<<month<<",日:"<<day<<endl;
}
小乙   1:40:52
把构造函数定义写到下边怎么不行啊？
Aaron  1:41:03
不会吧
小乙   1:41:04
#include <iostream>
using namespace std;

class DayOfYear
{
public:
    friend bool equal(DayOfYear date1,DayOfYear date2);   
    DayOfYear(int the_month,int the_day);
    DayOfYear();
    void input();
    void output();
    int get_month();
    int get_day();
private:
    void check_date();
    int month;
    int day;
};

int main ()
{
    DayOfYear today,bach_birthday(3,21);

    cout<<"输入今天日期：";
    today.input();
    cout<<"今天是";
    today.output();

    cout<<"xxx的生日是";
    bach_birthday.output();

    if(equal(today,bach_birthday))
        cout<<"happy!";
    else
        cout<<"unhappy!";

    return 0;
}

bool equal(DayOfYear date1,DayOfYear date2)
{
    return(date1.month == date2.month && date1.day ==date2.day);
}
DayOfYear::DayOfYear(int the_month,int the_day):month(the_month),day(the_day)
{
    //无动作
}
DayOfYear::DayOfYear()
{
}
int DayOfYear::get_month()
{
    return month;
}
int DayOfYear::get_day()
{
    return day;
}
//使用iosream
void DayOfYear::input()
{
    cout<<"输入月份：";
    cin>>month;
    cout<<"输入日期:";
    cin>>day;
}
void DayOfYear::output()
{
    cout<<"月:"<<month<<",日:"<<day<<endl;
}