use Perl

I found this lovely snippet of code while fixing* a broken script. I especially love how as a side effect it removes the spaces from $_.

sub Commify
{
  s/ //g;
        my $delimiter = ',';
        my($n,$d) = split /\./,shift,2;
        my @a = ();
        while($n =~ /\d\d\d\d/)
        {
                $n =~ s/(\d\d\d)$//;
                unshift @a,$1;
        }
        unshift @a,$n;
        $n = join $delimiter,@a;
        $n = "$n\.$d" if $d =~ /\d/;
        return $n;
}

*The sort of fixing that is done with rm.