Online PHP editor | refs for gPjD3

<?php $str = 'xxxx xxxx xx xxxx xxx foo xxx xxx xxxxx\nxxxx xx foo xxx xxx xxxxx\nxx xxxxx xxxx xx xxx xx bar xx xxxx\nxxxxxx xx xxxxx x xxxx bar\nxxx xxxxx xx xx foo_sub1 xxx xxxx\nxx foo_sub2 xxxxx xxx x xxxx\nxxx xx foo1_sub1 xxx xxxx\nxxxxx foo1_sub2 xxxxx xxx x xxxx'; if (preg_match_all('~\bfoo(?:_\w+)?\b~', $str, $matches)) { print_r($matches[0]); }