use warnings;
use strict;
use POSIX;

my $yday = (localtime())[7];

print "Today is $yday\n";

my $mday  = 25;
my $month = 12;
my $year  = 2010;

my $time_t = POSIX::mktime(0, 0, 0, $mday-1, $month-1, $year-1900);

my $cday = (localtime($time_t))[7];

print "Christmas day 2010 is day $cday\n";