C++编程之约定俗成的习惯（1）

说明：C++的类定义中，可以任意安排成员函数和成员变量的位置，一般我们将成员变量都设置成私有的，而将大多成员函数都设置为公有的。其中，公有成员和私有成员顺序的安排没有统一的标准，但是我们倾向于将成员函数放在成员变量之前。

代码示例：

//包含一个非常简单的类的演示程序//类DayOfYear#include<iostream>#include<cstdlib>using namespace std;class DayOfYear{public:    void input();    void output();    void set(int newMonth,int newDay);    //前提条件:newMonth和newDay可以构成一个合法的日期    void set(int newMonth);    //前提条件:1<=newMonth<=12    //运行结果: 日期被设定为参数给定月份的第一天    int geyMonthNumber();    int getDay();private:    int month;    int day;};int main(){    DayOfYear today,bachBirthday;    cout<<"Enter today's date:\n";    today.input();    cout<<"Today's date is ";    today.output();    cout<<endl;    bachBirthday.set(3,21);    cout<<"J.S Bach's birthday is ";    bachBirthday.output();    cout<<endl;    if(today.geyMonthNumber()==bachBirthday.geyMonthNumber()&&today.getDay()==bachBirthday.getDay())    {        cout<<"Happy Birthday Johann Sebastian!\n";    }    else    {        cout<<"Happy Unbirthday Johann Sebastian!\n";    }    return 0;}//使用iostream和cstdlibvoid DayOfYear::set(int newMonth,int newDay){    if((newMonth>=1)&&(newMonth<=12))    {        month=newMonth;    }    else    {        cout<<"Illegal month value!Program aborted.\n";        exit(1);    }    if((newDay>=1)&&(newDay<=31))    {        day=newDay;    }    else    {        cout<<"Illegal day value!Program aborted.\n";        exit(1);    }}void DayOfYear::set(int newMonth){    if((newMonth>=1)&&(newMonth<=12))    {        month=newMonth;    }    else    {        cout<<"Illegal month value!Program aborted.\n";        exit(1);    }    day=1;}int DayOfYear::geyMonthNumber(){    return month;}int DayOfYear::getDay(){    return day;}void DayOfYear::input(){    cout<<"Enter the month as a number:";    cin>>month;    cout<<"Enter the day of the month:";    cin>>day;    if((month<1)||(month>12)||(day<1)||(day>31))    {        cout<<"Illegal date!Program aborted.\n";        exit(1);    }}void DayOfYear::output(){    switch(month)    {    case 1:        cout<<"January ";        break;    case 2:        cout<<"February ";        break;    case 3:        cout<<"March ";        break;    case 4:        cout<<"April ";        break;    case 5:        cout<<"May ";        break;    case 6:        cout<<"June ";        break;    case 7:        cout<<"July ";        break;    case 8:        cout<<"August ";        break;    case 9:        cout<<"September ";        break;    case 10:        cout<<"October ";        break;    case 11:        cout<<"November ";        break;    case 12:        cout<<"Decemebr ";        break;    default:        cout<<"Error in DayOfYear::output.";    }    cout<<day;}