Validate number of days in a given month

Question

Performance is of the utmost importance on this one guys... This thing needs to be lightning fast!


How would you validate the number of days in a given mont

Answer 1

I'm mostly agreeing w/ Moayad. I'd use a table lookup, with an if check on February and the year.

pseudocode:

Last_Day = Last_Day_Of_Month[Month];
Last_Day += (Month == February && Leap_Year(Year)) ? 1 : 0;

Note that Leap_Year() can't be implemented simply as (Year % 4 == 0), because the rules for leap years are way more complex than that. Here's an algorithm cribbed from Wikipedia

bool Leap_Year (int year) {
   return ((year % 4 == 0) && (year % 100 != 0)) || (year % 400 == 0);
}