怎样能实现实现日期加一

为啥得到的结果不对为啥得到的结果不对
为啥得到的结果不对为啥得到的结果不对

改两个地方

d.nextDay(1);

void Date::nextDay(int loop)
{
   if( day >= 1&& day < monthDays())
   {
      day=day+loop;
    }
   else
   {
         if(day==monthDays() && month!=12)
         {
             day=day+loop-monthDays();
             month+=1;
      }
         if(month==12)
         {
             year+=1;
        month = 1;
        day= 1;
      }
   }
    setDay(day); 
    setMonth(month);
    setYear(year);
    getDay();
    getMonth();
    getYear(); 
   /* Write code to define member function nextDay;
   make sure to check if the new day is the start of
   a new month or a new year */
}