php计算整个目录大小的方法

/**
 * calculate the full size of a directory
 *
 * @author   jonas john
 * @version   0.2
 * @param    string  $directorypath  directory path
 */
function calcdirectorysize($directorypath) {
  // i reccomend using a normalize_path function here
  // to make sure $directorypath contains an ending slash
  // to display a good looking size you can use a readable_filesize
  // function.
  $size = 0;
  $dir = opendir($directorypath);
  if (!$dir)
    return -1;
  while (($file = readdir($dir)) !== false) {
    // skip file pointers
    if ($file[0] == '.') continue; 
    // go recursive down, or add the file size
    if (is_dir($directorypath . $file))      
      $size += calcdirectorysize($directorypath . $file . directory_separator);
    else 
      $size += filesize($directorypath . $file);    
  }
  closedir($dir);
  return $size;
}
//使用范例：
$sizeinbytes = calcdirectorysize('data/');