Sort an array by child value

$arr = array(
array(“translationID” => “1”,”locale” => “nl_BE”,”translation” => “U bent aangemeld”),
array(“translationID” => “2”,”locale” => “de_DE”,”translation” => “Sie sind angemeldet als”)
);

function cmp($a, $b) {
if ($a[“locale”] == $b[“locale”]) {
return 0;
}
return ($a[“locale”] < $b[“locale”]) ? -1 : 1;
}
usort($arr,”cmp”);