$re = '/\bi\K(?:pad|phone)\b|[a-z]+/';
$str = 'the ipad has gone out of stock
power up your iphone
what model is your apple iphone
---
strings with monkeywrenching words...
fly the chopper to the helipad
an audiphone is a type of hearing aid
consisting of a diaphragm that, when
placed against the upper teeth, conveys
sound vibrations to the inner ear';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php