#!/usr/bin/env perl

use strict;
use warnings;

my @number_names = qw{zero one two three four five six seven eight nine};
my $pattern = qr{ ( [0-9] ) }x;

my @strings = ('8, 9, 5', '3-2-1-0', 'Testing: 1 2 3');

for my $string (@strings) {
    print "DIGITS: $string\n";
    $string =~ s/$pattern/$number_names[$1]/g;
    print "NAMES:  $string\n";
}

##</code><code>##

DIGITS: 8, 9, 5
NAMES:  eight, nine, five
DIGITS: 3-2-1-0
NAMES:  three-two-one-zero
DIGITS: Testing: 1 2 3
NAMES:  Testing: one two three