RE: simple stupid time question

I'd just write a simple routine to do it. Something like the following wouldn't be awful, in a dozen lines of code or so:

sub days_in_month {
    my $month = shift;
    my $year = shift;
    my @mdays = qw( 31 28 31 30 31 30 31 31 30 31 30 31 );

    if ($month == 2) {
        if ($year % 4 == 0) {    # normal leap year
            if ($year % 100 == 0) { # century year, not a leap year
                return 28 unless 
                ($year % 400 == 0); # century AND leap year
            }
        return 29;
        }
    }
    return $mdays[$month - 1];    # fudge the index
}
[download]

Update: Foggy and Adam contributed the current state of (now tested) not-so-bugginess. Seems like I should have actually *looked it up* in my library before I tried to recreate this wheel from memory.

I originally intended this to be straightforward teaching code, but Adam's second snippet is much better.

Comment on RE: simple stupid time question Download Code

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RE: RE: simple stupid time question by Adam (Vicar) on Sep 14, 2000 at 22:45 UTC
Your leap year code is still wrong. It should be: `if ($month == 2) { if ( ( $year % 4 == 0 ) # normal leap year && ( ( $year % 100 != 0 ) # century year \|\| ( $year % 400 == 0 ) # leap century ) ) { return 29; } }` [download] Also, you declare `my $days = 0` but you don't use it. Update: All those parens are ugly, how about: `if( 2 == $month ) { return 29 if 0 == $year % 4 and 0 != $year % 100 or 0 == $year % 400; }` [download] That works thanks to short circuitry and precedence. (yeah I could remove the 0 != part, but I wanted to retain explicit readability.) I think the leap year formula has become a frequently asked question, so I posted the answer here as well. Update: Chromatic's code will now work. It a slightly different way to look at it, using `if` and `unless`, but it works.	[reply] [d/l] [select]
RE: RE: simple stupid time question by Fastolfe (Vicar) on Sep 14, 2000 at 17:38 UTC
Is it possible for a leap century to occur on a leap year? Couldn't you get 30 days in February as a result? I'm wondering if there isn't already a module that does this...	[reply]
RE: RE: RE: simple stupid time question by spudzeppelin (Pilgrim) on Sep 14, 2000 at 18:53 UTC
Nope, you can't have a 30-day February specifically because the construct actually looks like: `if ((($year % 4) = 0) && (($year % 100) != 0)) { $feb += 1; } #leap year elsif (($year % 400) = 0) { $feb +=1; } #leap century` [download] So, since a regular "leap year" doesn't occur at the end of a century, the two conditions are never simultaneously satisfied. Spud Zeppelin * spud@spudzeppelin.com	[reply] [d/l]