Printf and commas

From the perlFAQ:

How can I output my numbers with commas added?

This one will do it for you:

    sub commify {
        local $_  = shift;
        1 while s/^(-?\d+)(\d{3})/$1,$2/;
        return $_;
    }

    $n = 23659019423.2331;
    print "GOT: ", commify($n), "\n";

    GOT: 23,659,019,423.2331

You can't just:

    s/^(-?\d+)(\d{3})/$1,$2/g;

because you have to put the comma in and then recalculate your position.

Ok - not what I wanted to hear because I am not using Perl, long story, but oh well.   Thanks - please submit as an answer.

Thanks.