I'm interested to know if there's a "simpler" way to do this - ideally getting rid of the super-hideous while loop

How about a recursive solution?

sub commify
{
    my($num) = @_;
    return $num if length($num)<4;
    return commify(substr($num,0,-3), $len).",".substr($num,-3,3);
}
[download]

...no super-hideous while loop there, and no regex compilation either. ;-)

The only downside is that this only works for integers.

--
hiseldl
What time is it? It's Camel Time!