#!/usr/bin/perl

# http://perlmonks.org/?node_id=1183627

use strict;
use warnings;

$_ = '222,345,222,678,222,222,543,111';

while( /222,(\d\d\d)/g )
  {
  print "AFTER 222-$1\n";
  pos($_) -= 4; # actually move back 4 characters
  }