Re^2: Stuck in komplexer regex, at least for me

(for the regex fanboys:

sub compress_numstring {
  substr($_[0], 2) =~ s/(^0+|(0)0+|(?<!0)0([1-9]|$))/$2$3/;
  return $_[0];
}
[download]

does the same thing as the other function, but with more job security)
Unfortunately, 'use warnings' will complain.