Leap Year

Every now and then I find someone that still believes leap days come in 4 year cycles, no exception made. Some of them are even programmers that never had to implement a leap year algorithm:

    public static class DateUtils
    {
        public static bool IsLeapYear(this int year)
        {
            return (year % 400 == 0) || ((year % 4 == 0) && (year % 100 != 0));
        }
    }

 

I used to get quite nervous with the fact, but not anymore. Why? This just doesn’t impact on today’s every days life :) Let me try and prove it to you:

            foreach (
                var year in 
                    Enumerable.Range(1582, 1500)
                    .Where(d => (d % 4 == 0) && d.IsLeapYear() == false)
            )
            {
                Console.WriteLine("{0}", year);
            }

So what am I getting? On the first 1500 years since the Gregorian calendar as defined the present algorithm, which of these 4 year cycles weren’t leap years?

 

Oops, it seems like no one I know was born of probably be alive on those days, who cares? “Press any key to continue”: yeap, seems right :)