作业

#include <iostream>    using namespace std;   class Time  {  public:      void set_time();  void show_time();  inline add_a_sec();  inline add_a_minute();  inline add_a_hour();//内置函数，增加一秒  add_seconds(int);      add_minutes(int);  add_hours(int);//增加N秒  private:  bool is_time( int, int, int);  int hour;  int minute;  int sec;  };    int main()    {        Time t1;              Time &t2 = t1;              t1.set_time();             t2.show_time();              t1.add_a_sec();              cout << "增加1秒钟：" << endl;            t2.show_time();              t1.add_a_minute();            cout << "增加1分钟：" << endl;            t2.show_time();              t1.add_a_hour();              cout << "增加1小时：" << endl;           t2.show_time();              t1.add_seconds(45);             cout << "增加45秒钟：" << endl;            t2.show_time();              t1.add_minutes(50);              cout << "增加50分钟：" << endl;            t2.show_time();              t1.add_hours(2);              cout << "增加2小时：" << endl;            t2.show_time();              return 0;  }  ;    void Time::set_time()  {      char c1,c2;      cout << "请输入时间：格式 (hh:mm:ss)";      while(1)      {          cin >>hour>>c1>>minute>>c2>>sec;                    if (c1!=':'||c2!=':')          {              cout << " 时间格式不正确，请重新输入！" <<endl;          }                    else if(!is_time(hour,minute,sec))          {              cout << "时间非法，重新输入！" <<endl;          }                    else           {              break;          }                }  }    int Time::add_a_sec()  {      sec = sec+1;            return sec;  }    int Time::add_a_minute()  {      minute = minute+1;      return minute;  }    int Time::add_a_hour()  {      hour= hour+1;      return hour;  }    int Time::add_seconds(int n)  {      sec=sec+45;      return sec;        }    int Time::add_minutes(int n)  {      minute=minute+50;      return minute;  }  int Time::add_hours(int)  {      hour=hour+2;  return hour;  }    void Time::show_time()  {      if(sec>59 && minute<59)      {          minute=minute+sec/60;          sec=sec%60;          cout <<hour<<":"<<minute<<":"<<sec <<endl;      }       else if(minute>59&&hour<23)      {          hour=hour+minute/60;          minute=minute%60;          cout <<hour<<":"<<minute<<":"<<sec << endl;      }        else if(hour>23)      {          hour=0;          minute=0;          sec=0;          cout <<"第二天"<<hour<<minute<<sec<<endl;      }      else      {    cout <<hour<<":"<<minute<<":"<<sec <<endl;      }  }  bool Time::is_time(int h,int m,int s)  {     if(h<0||h>24||m<0||m>60||s<0||s>60)          return false;    return true;  }