If you look into it you will find that people differ on how they interpret that (largely depending on where they are from). In fact there are other combinations possible, I am not sure how many are in common use. The above two are just the ones that I have lived with.

For that reason if at all possible I suggest going with the ISO standard 2001-04-09 (or 2001-09-04 if you meant the other thing).

Wins. First of all nobody that I know of finds that at all confusing. Secondly when you come back wanting to sort these dates it will be easy because we will all tell you to sort, and alphabetical order will be right. Thirdly if you ever need to compare dates it will be trivial to tell what comes first.

So, less work for you. Doesn't confuse anybody. And it is actually an ISO standard. What is not to like? :-)

printf("%02d/%02d/%02d", $month, $day, $year); If you're setting those variable straight from localtime(), and want to avoid displaying "04/13/101" intsead of "05/13/01", best use   printf("%02d/%02d/%02d", $mon + 1, $mday, $year % 100);

++tilly on the ISO date advocacy post.

I'm not a big fan of using sprintf or other home-grown methods for formatting date strings. IMHO, it's much cleaner to use CPAN's Date::Format module. You get clearer code, and more consistent results:

#!/usr/bin/perl -w

use strict;
use Date::Format;

my $iso_date = time2str '%Y-%m-%d', time;
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This will return the date in ISO format: YYYY-MM-DD

my @date = localtime;
$date[4]++;
$date[5]%=100;
printf("European: %02d/%02d/%02d\n",@date[3,4,5]);
printf("US/Canada/???: %02d/%02d/%02d\n",@date[4,3,5]);
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