#!/usr/bin/perl
@dates = ('20130401', '20130501', '20130601');
@ordered = sort { &compare } @dates;
sub compare {
$a =~ /(\d{4})(\d{2})(\d{2})/;
$c = $3 . $2 . $1;
$b =~ /(\d{4})(\d{2})(\d{2})/;
$c = $3 . $2 . $1;
$c <=> $d;
}
print "@ordered\n";

##</code><code>##

20130501 20130401 20130601

##</code><code>##

20130501 20130401 20130601