C++作业2

#include <iostream>
using namespace std;
class Time
{
public:
void set_time( );
void show_time( );
void add_seconds(int);
void add_minutes(int);
void add_hours(int);
void add_a_sec()
{
sec+=1;
if(sec>=60)
{
sec=00;
minute+=1;
}
show_time( );
}
void add_a_minute()
{
minute+=1;
if(minute>=60)
{
minute=00;
hour+=1;
}
show_time( );
}
void add_an_hour()
{
hour+=1;
if(hour>24)
hour=01;
show_time( );
}
private:
bool is_time(int, int, int);   //这个成员函数设置为私有的，是合适的，请品味
int hour;
int minute;
int sec;
};
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<<"格式不正确，请重新输入"<<endl;
else if (!is_time(hour,minute,sec))
cout<<"时间非法，请重新输入"<<endl;
else
break;
}
}
void Time::show_time( )
{
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;
}
void Time::add_seconds(int n)
{
sec+=n;
if(sec>=60)
{
sec=sec%60;
minute=sec/60;
}
if(minute>=60)
{
minute=minute%60;
hour=hour+minute/60;
}
show_time();
}
void Time::add_minutes(int n)
{
minute+=n;
if(minute>=60)
{
minute=minute%60;
hour=hour+minute/60;
}
show_time();
}
void Time::add_hours(int n)
{
hour+=n;
if(hour>24)
hour=hour%24;
show_time();
}
int main()
{
Time t1,t2,t3,t4,t5,t6;
int n;
t1.set_time();
t1.show_time();
t2=t1;
t3=t1;
t4=t1;
t5=t1;
t6=t1;
t1.add_a_sec();
t2.add_a_minute();
t3.add_an_hour();
cin>>n;
t4.add_seconds(n);
t5.add_minutes(n);
t6.add_hours(n);
return 0;
}