"How can I output my numbers with commas added?" question in perlfaq5

Regarding the "How can I output my numbers with commas added?"
question in perlfaq5; here's an even simpler way to achive the same:

sub commify {
        local $_ = reverse shift;
        s/(\d{3})(?=\d)(?!\d*\.)/$1,/g;
        scalar reverse;
}