Actually your solution is quite good, if you just want the time and don't want to use outside modules (i.e. Date::Calc which doesn't do you much good anyway for this problem). You do have a small bug though ... what if it is 12 NOON? With your code

if($hh > 12) { # hh = 12;
     $hh = $hh - 12;
     $ampm = "PM";
}
else {
     $ampm = "AM"; # opps 12 PM just became 12 midnight.
}
[download]

Test to see if the hour is 12 and set the $ampm to "PM" in that case without subtracting anything.

Hope that helps
Chris