use POSIX qw(strftime);

use strict;
use warnings;

my @date = localtime;

while (<DATA>) {
	my ($year, $mon, $day, $expected) = split;
	
	@date[3,4,5] = ($day, $mon, $year);
	my $fmt = strftime "%Y%m%d", @date;
	
	print "$fmt <=> $expected " . ($fmt eq $expected ? 'matched' : 'failed') . "\n";
}

=prints
20110501 <=> 20110501 matched
20110430 <=> 20110430 matched
20110429 <=> 20110429 matched
20110102 <=> 20110102 matched
20110101 <=> 20110101 matched
20110512 <=> 20101231 failed
20110512 <=> 20101230 failed
=cut

__DATA__
111 4 1 20110501
111 4 0 20110430
111 4 -1 20110429
111 0 2 20110102
111 0 1 20110101
111 0 0 20101231
111 0 -1 20101230