Re: date %d day question

[Greg Wooledge]

On Wed, Oct 30, 2024 at 01:17:28 +0100, #!microsuxx wrote:
> hm very weird
> i cant find googling or ai'ing once a reference ...
> i think we here learned in school , and it got used ( eg in years of my
> life )
> every 4 years theres one month with one more day eg 32
> .... ill tell u when i find out
> .. prolly an other day

February has 28 days, except in "leap years", where it has 29 days.

Leap years occur every 4th year, except for years ending in 00 which
aren't divisible by 400.  In pseudocode, it works like this:

    if (year % 400 == 0)
        this is a leap year

    else if (year % 100 == 0)
        this is NOT a leap year

    else if (year % 4 == 0)
        this is a leap year

    else
        this is NOT a leap year

2024 is a leap year.  2000 was a leap year, but 2100 will not be.

The estimate of "every 4th year" was used before the Gregorian calendar,
and it turned out to be noticeably wrong.  The adjustment to remove 3
leap years every 400 years is what differentiates the Gregorian calendar
from the Julian calendar that was used previously.