如何从SaveFileDialog.FileName中仅获取目录名称

using System;
using System.IO;

class Program
{
    static void Main()
    {
        SaveFileDialog dialog = new SaveFileDialog();
        dialog.ShowDialog();

        string fileName = dialog.FileName;
        string directoryName = Path.GetDirectoryName(fileName);

        Console.WriteLine("目录名称: " + directoryName);
    }
}