use Date::Simple qw/today/;
print today() + 5, "\n";
print today() + 9, "\n";
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... assuming I understood the question correctly.

In addition to the good answer from moritz:

I prefer Date::Calc for all my Date-calculations. It may be overhead in your case, but I like the idea of having only one Date-module to learn ;-) Date::Calc offers a function called Add_Delta_Days which serves your purpose.

HTH, Rata

Update:WOW! I thought I was pretty fast with typing my answer ... but 5 monks were faster! I'm impressed!

If you are not using DateTime, how are you representing your dates?

sleep (5*24*60*60);
my $after5date = localtime(time);
print $after5date;
sleep (4*24*60*60);
my $after4days = localtime(time);
print $after4days;
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Not all days have 24 hours. Fix below. This will also give you the answer up to 23.5 hours sooner.

use POSIX qw( strftime );

sub next_day {
   my $start_d = (localtime)[3];
   for (;;) {
      sleep(30*60);
      my $d = (localtime)[3];
      return if $d != $start_d;
   }
}

next_day() for 1..5;
print strftime("%Y-%m-%d\n", localtime());

next_day() for 1..4;
print strftime("%Y-%m-%d\n", localtime());
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Suffers from a race-condition that manifests itself if the loops is started very shortly before midnight.

Add_Delta_Days
      ($year,$month,$day) =
      Add_Delta_Days($year,$month,$day,
                     $Dd);
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my $dt = DateTime->today( time_zone => 'local' );

$dt->add( days => 5 );
print $dt->ymd(), "\n";

$dt->add( days => 4 );
print $dt->ymd(), "\n";
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I prefer this.

Check for Date::Time documentation for some more methods.

I used DateTime, not Date::Time

My personal favorite is Date::Manip ... but the real point here is that there are several good modules already out there for doing date/time manipulation.   If, for example, what you want is “five business days from now, excluding the legal holidays of Croatia,” then there is probably a CPAN routine out there now which will do it.