模拟获取份额大小的过程

我编写了一些代码来模拟获取共享驱动器大小的过程。驱动器来自一个文本文件。问题是这些路径到达了一个超过250的阶段?charachter极限。这是可以避免的吗?

我在网上找到一些建议放置@"'?'"之前的文件路径，但我不确定它是否会为定义工作，如果我使用它正确与否?

感谢

        void getSizes_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
            String val = "";
            float megabytes = ((float)e.Result / 1024f) / 1024f;
            if (megabytes > 10240) //greater than 10 gig
                val = (megabytes / 1024.0).ToString() + "GB";
            else
                val = megabytes + "MB";
            textBox1.Text += val;
            textBox1.Text += Environment.NewLine;
        }
        void getSizes_DoWork(object sender, DoWorkEventArgs e)
        {
            String s = (String)e.Argument;
            String path = Path.GetFullPath(s);
            float bytes = (float)GetDirectorySize((String)e.Argument);
            e.Result = bytes;
        }
        protected static float GetDirectorySize(string folder)
        {
            float folderSize = 0.0f;
            try
            {
                //Checks if the path is valid or not
                if (!Directory.Exists(folder))
                    return folderSize;
                else
                {
                    try
                    {
                        foreach (string file in Directory.GetFiles(folder))
                        {
                            String path = @"''?'" + file;
                            if (File.Exists(path))
                            {
                                FileInfo finfo = new FileInfo(path);
                                folderSize += finfo.Length;
                            }
                        }
                        foreach (string dir in Directory.GetDirectories(folder))
                            folderSize += GetDirectorySize(dir);
                    }
                    catch (NotSupportedException e)
                    {
                        Console.WriteLine("Unable to calculate folder size: {0}", e.Message);
                    }
                }
            }
            catch (UnauthorizedAccessException e)
            {
                Console.WriteLine("Unable to calculate folder size: {0}", e.Message);
            }
            return folderSize;
        }
    }
}