I don't dare to imagine how damned complicate it would be to do this, say, in C.

It would be more work in C. I fail to see that a solution in C would be simpler if one can assume the numbers are smaller than 10, or that the string is limited to 20 characters.

Personally I do not share this somewhat elitarist attitude.

Well, I think there's no excuse for sloppy code at all. Not on Perl monks, and not outside Perl monks either.