php怎么递归删除空数组

function array_remove_empty($arr){
 $narr = array();
 while(list($key, $val) = each($arr)){
  if (is_array($val)){
   $val = array_remove_empty($val);
   // does the result array contain anything?
   if (count($val)!=0){
    // yes :-)
    $narr[$key] = $val;
   }
  }
  else {
   if (trim($val) != ""){
    $narr[$key] = $val;
   }
  }
 }
 unset($arr);
 return $narr;
}

array_remove_empty(array(1,2,3,'',array(),4)) => returns array(1,2,3,4)