c++作业3

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一、静态成员类

/*     * 文件名称：静态成员类     * 作    者：刘丽      * 完成日期：2016年4月11日     * 版 本 号：v1.0     * 对任务及求解方法的描述部分:    * 输入描述：      * 问题描述：设计含有静态数据成员和成员函数的Time类  * 程序输出： 略    * 问题分析： 略    * 算法设计： 略    */    #include <iostream>using namespace std;class Time{public:    Time(int=0,int=0,int=0);    void show_time( ); //根据is_24和from0，输出适合形式-20:23:5/8:23:5 pm/08:23:05 pm    void add_seconds(int); //增加n秒钟    void add_minutes(int); //增加n分钟    void add_hours(int); //增加n小时    static void change24();  //改变静态成员is_24，在12和24时制之间转换    static void changefrom0();   //改变静态成员from0，切换是否前导0private:    static bool is_24; //为true时，24小时制，如20:23:5；为flase，12小时制，显示为8:23:5 pm    static bool from0; //为true时，前导0，8:23:5显示为08:23:05    int hour;    int minute;    int sec;};Time::Time(int h, int m, int s){    hour = h, minute = m, sec = s;}bool Time::is_24 = true;bool Time::from0 = false;void Time::show_time( ){    if (is_24)    {        if (from0)        {            cout << (hour < 10 ? "0":"") << hour << ':'                << (minute < 10 ? "0":"") << minute << ':' << (sec < 10 ? "0":"") << sec << endl;        }        else        {            cout << hour << ':' << minute << ':' << sec << endl;        }    }    else    {        if (from0)        {            cout << (hour < 10||(hour - 12 >=0 && hour - 12 < 10) ? "0":"") << (hour > 12 ? hour-12 : hour) << ':' << (minute < 10 ? "0":"") << minute << ':' << (sec < 10 ? "0":"") << sec << ' '  << (hour > 11 ? "pm" : "am") << endl;        }        else        {            cout << (hour > 12 ? hour-12 : hour) << ':'<< minute<< ':' << sec << ' ' << (hour > 11 ? "pm" : "am") << endl;        }    }}void Time::add_seconds(int s){    s = sec + s;    sec = s % 60;    add_minutes(s / 60);}void Time::add_minutes(int m){    m = minute + m;    minute = m % 60;    add_hours(m / 60);}void Time::add_hours(int h){    h = hour + h;    hour = h % 24;}void Time::change24(){    is_24 = !is_24;    if (is_24) cout << "已切换为24小时制。" << endl;    else cout << "已切换为12小时制。" << endl;}void Time::changefrom0(){    from0 = !from0;    if (from0) cout << "已切换为前导0输出。" << endl;    else cout << "已切换为非前导0输出。" << endl;}int main( ){    Time t1(23, 14, 25), t2(8, 45, 6);    cout << "24时制, 不前导0：" << endl;    cout << "    t1是：";    t1.show_time();    cout << "    t2是：";    t2.show_time();    t1.add_hours(10);    t2.add_hours(10);    Time::changefrom0();    cout << "10小时后, 切换是否前导0：" << endl;    cout << "    t1是：";    t1.show_time();    cout << "    t2是：";    t2.show_time();    t1.change24();    cout << "换一种制式：" << endl;    cout << "    t1是：";    t1.show_time();    cout << "    t2是：";    t2.show_time();    return 0;}

二、友元类

#include<iostream>using namespace std;class Date; //对Date类的提前引用声明class Time{public:    Time(int,int,int);    void add_a_second(Date &d);  //增加1秒，1秒后可能会到了下一天，乃到下一月、下一年    void display(Date &d);  //显示时间，格式：月/日/年 时:分:秒private:    int hour;    int minute;    int sec;};class Date{public:    Date(int,int,int);    friend class Time; //Time为Date的友元类private:    int month;    int day;    int year;};int day(int,int);Time::Time(int h,int m,int s){    hour=h;    minute=m;    sec=s;}Date::Date(int m,int d,int y){    month=m;    day=d;    year=y;}void Time::add_a_second(Date &d){    sec++;    if(sec>=60)    {        minute++;        sec=0;    }    if(minute>=60)    {        hour++;        minute=0;    }    if(hour>=24)    {        d.day++;        hour=1;    }    if(d.day>31)    {        d.month++;        d.day=1;    }    if(d.month>12)    {        d.year++;        d.month=1;    }}void Time::display(Date &d){    cout<<d.year<<"年"<<d.month<<"月"<<d.day<<" "<<hour<<":"<<minute<<":"<<sec<<endl;}int main( ){    Time t1(23,59,32);    Date d1(12,31,2013);   //测试时，再试试Date d1(2,28,2013)会如何    for(int i=0; i<=100; i++)    {        t1.add_a_second(d1);        t1.display(d1);    }    return 0;}

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