dni w miesiacu

const int daysinmonths[] = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
int daysInMonth(int year, int month)
{
 if(month == 2 && ((year%4==0 && year%100!=0) || year%400==0))
   return 29;
 return daysinmonths[month-1];
}