如何循环指定文件夹中的所有文件夹？急！！

/// <summary>
    /// 拷贝目录（包含子目录及所有文件）
    /// </summary>
    /// <param name="sourceDirName">源文件目录名</param>
    /// <param name="destDirName">目标文件目录名</param>
    /// <param name="copySubDirs">是否拷贝子目录</param>
    internal static void DirectoryCopy(
        string sourceDirName, string destDirName, bool copySubDirs)
    {
        DirectoryInfo dir = new DirectoryInfo(sourceDirName);
        DirectoryInfo[] dirs = dir.GetDirectories();

        // If the source directory does not exist, throw an exception.
        if (!dir.Exists)
        {
            throw new DirectoryNotFoundException(
                "Source directory does not exist or could not be found: "
                + sourceDirName);
        }

        // If the destination directory does not exist, create it.
        if (!Directory.Exists(destDirName))
        {
            Directory.CreateDirectory(destDirName);
        }

        // Get the file contents of the directory to copy.
        FileInfo[] files = dir.GetFiles();

        foreach (FileInfo file in files)
        {
            // Create the path to the new copy of the file.
            string temppath = (destDirName, file.Name);

            // Copy the file.
            file.CopyTo(temppath, false);
        }

        // If copySubDirs is true, copy the subdirectories.
        if (copySubDirs)
        {
            foreach (DirectoryInfo subdir in dirs)
            {
                // Create the subdirectory.
                string temppath = (destDirName, subdir.Name);

                // Copy the subdirectories.
                DirectoryCopy(subdir.FullName, temppath, copySubDirs);
            }
        }
    }