#!/usr/bin/env perl
use strict;
use warnings;

my %english_of = (
   '+' => 'plus',
   '-' => 'minus',
   '*' => 'times',
   '/' => 'divided by',
);

my $string;

do {

   print "Please enter a string:\n";
   chomp ($string = <STDIN>);

   print "four-letter word: '$1'\n"
      if $string =~ / ([a-zA-Z]{4}) /;

   print "address: user = '$1', domain = '$2'\n"
      if $string =~ /([a-zA-Z]+)\@([a-zA-Z]+(?:\.[a-zA-Z]+)+)/;

   print "five-digit number: '$1$2'\n"
      if $string =~ /(?:^|\D)(\d{2}),?(\d{3})(:?\D|$)/;

   print "$string\n"
      if $string =~ s/([+\-*\/])/$english_of{$1}/;

} until $string =~ /done/;