问如何通过将文件名增加一个来列出其中的文件？

EN

    private string[] dirs;
    private string[] files;
    private System.IO.FileInfo file;
    private void GetPDF(string path, ref List<string> listPDF)
    {
        try
        {
            dirs = System.IO.Directory.GetDirectories(path);
            foreach (string item in dirs)
            {
                GetPDF(item, ref listPDF);
            }

            files = System.IO.Directory.GetFiles(path);
            foreach (string item in files)
            {
                file = new System.IO.FileInfo(item);
                if (file.DirectoryName.ToLower().EndsWith("test") && file.Extension.ToLower() == ".pdf")
                {
                    listPDF.Add(file.FullName);
                }
            }
        }
        catch (Exception)
        {
            throw;
        }
    }

    private void Function1()
    {
        try
        {
            System.Windows.Forms.FolderBrowserDialog dialog = new System.Windows.Forms.FolderBrowserDialog();
            if (dialog.ShowDialog() == System.Windows.Forms.DialogResult.OK)
            {
                List<string> listPDF = new List<string>();
                GetPDF(dialog.SelectedPath, ref listPDF);
                listPDF.Sort();
                foreach(string filePath in listPDF)
                {
                    Console.WriteLine(filePath);
                }
            }
        }
        catch (Exception)
        {
            throw;
        }
    }