my $today_wday = (localtime)[6];
my $then_wday  = ($today_wday + $days_in_the_future) % 7;

##</code><code>##

use Time::Local;

my $string      = "01-01-2015";
my ($m, $d, $y) = split /-/, $string;

my $epoch       = timelocal 0, 0, 0, $d, $m-1, $y-1900;
my $wday        = (localtime $epoch)[6];