Strict Standards: Only variables should be passed by reference

function medium($name) {
    $ext = strrchr($name, '.');
    if($ext !== false) {
        $name = substr($name, 0, -strlen($ext)) . "_medium." . end(explode('.',$name));   //อยากแยกบรรทัดนี้
    }
    return $name;
  }

  function thumb($name) {
    $ext = strrchr($name, '.');
    if($ext !== false) {
        $name = substr($name, 0, -strlen($ext)) . "_thumb." . end(explode('.',$name)); //อยากแยกบรรทัดนี้
    }
    return $name;
  }