use strict;
use warnings;

my $first  = "11/15/2007";
my $second = "12/25/2007";

use POSIX qw/mktime/;
sub days_between {
        my ($start, $end) = @_;
        my ($m1, $d1, $y1) = split ("/", $start);
        my ($m2, $d2, $y2) = split ("/", $end);
        my $diff = mktime(0,0,0, $d2-1, $m2-1, $y2 - 1900) -  mktime(0,0,0, $d1-1, $m1-1, $y1 - 1900);
        return $diff / (60*60*24);
}

print "Between $first and $second there are ", days_between($first, $second), " days\n";