<?php $array = array('cat', 'hat', 'sat'); $iterator = new ArrayIterator($array); # Simple regex $regexIterator = new RegexIterator($iterator, '/.at/'); var_dump($regexIterator->getRegex()); # Empty regular expression $regexIterator = new RegexIterator($iterator, '//'); var_dump($regexIterator->getRegex()); # "Complex" email regular expression $regexIterator = new RegexIterator($iterator, '|\\b[A-Z0-9._%-]+@[A-Z0-9.-]+\\.[A-Z]{2,4}\\b|'); var_dump($regexIterator->getRegex());