- ltrim: documentation ( source)
- strtolower: documentation ( source)
<?php
$s = array('Astreet','bstreet','cstreet','dstreet','estreet','fstreet','gstreet','hstreet','istreet');
for($i=0;;print(strlen($s[$i])==strlen(ltrim(strtolower($s[$i++]),'aeiou'))?left:right)){}