文件大小格式化

//文件大小格式化
public function fileSizeFormat($size = 0, $dec = 2) {
      $unit = array("B", "KB", "MB", "GB", "TB", "PB");
      $pos = 0;
      while ($size >= 1024 && $pos <= 5) {
          $size /= 1024;
          $pos++;
      }

      $result['size'] = round($size, $dec);
      $result['unit'] = $unit[$pos];
      return $result['size'] . $result['unit'];
}