my ($a, $b, $c, $d, $e) = ("aaa", "ab000", "123", "00123", "321ba",);
$a++;
$b++;
$c++;
$d++;
$e++;
print "a=$a\nb=$b\nc=$c\nd=$d\ne=$e\n"
[download]

You'll notice when you run those that $e gets chopped to just numbers. In fact, my stunting isn't really necessary since perl will happily leave the "00" on the front of $d! The only trick to it is never treating $d as a number. Look at this:

# now that is golfing.
perl -e '$a="0035";until("$a">50){print++$a,$/}'
[download]

Cute huh? Perl is like a squirrel's nest. Good stuff is everywhere but most of it is nuts...

Your code could be re-updated to have quotes around "$String" in the comparison for the loop and just have $String++ where the "magical" part was. Sad that I didn't even know how slick it was. My stunt kept the comparison from blasting the string but it is better just to never treat it numerically.

--
$you = new YOU;
honk() if $you->love(perl)