c# - “字符串”不包含/的定义

Question

错误：
 'string'不包含'SelectedPath'的定义，找不到扩展方法'SelectedPath'接受类型为'string'的第一个参数

码：

 private static string fbd = String.Empty;
    public void button2_Click(object sender, EventArgs e)
    {
        FolderBrowserDialog fbd = new FolderBrowserDialog();
        fbd.Description = "Select a Folder to save the images.";
        if (fbd.ShowDialog() == System.Windows.Forms.DialogResult.OK)
            textBox1.Text = fbd.SelectedPath;
    }

public void button3_Click(object sender, EventArgs e)
    {

        List<string> address = new List<string>();
        Random r = new Random();
        address.Add("http://d24w6bsrhbeh9d.cloudfront.net/photo/4600000_460s.jpg");
        address.Add("http://d24w6bsrhbeh9d.cloudfront.net/photo/4600001_460s.jpg");
        address.Add("http://d24w6bsrhbeh9d.cloudfront.net/photo/4600002_460s.jpg");
        address.Add("http://d24w6bsrhbeh9d.cloudfront.net/photo/4600003_460s.jpg");
        //MessageBox.Show(address[r.Next(0, 4)]);

        if (comboBox1.Text == "10")
        {
            string filename = fbd.SelectedPath;
            MessageBox.Show(fbd);

            HttpWebRequest request = (HttpWebRequest)WebRequest.Create(new Uri(address[r.Next(0, 4)]));
            HttpWebResponse response = (HttpWebResponse)request.GetResponse();

            if ((response.StatusCode == HttpStatusCode.OK ||
                response.StatusCode == HttpStatusCode.Moved ||
                response.StatusCode == HttpStatusCode.Redirect) &&
                response.ContentType.StartsWith("image", StringComparison.OrdinalIgnoreCase))
            {

                using (Stream inputStream = response.GetResponseStream())
                using (Stream outputStream = File.OpenWrite(filename))
                {
                    byte[] buffer = new byte[4096];
                    int bytesRead;
                    do
                    {
                        bytesRead = inputStream.Read(buffer, 0, buffer.Length);
                        outputStream.Write(buffer, 0, bytesRead);
                    } while (bytesRead != 0);
                    using (WebClient client = new WebClient())
                    {
                        client.DownloadFile(address[r.Next(0, 25)], filename);
                    }

                }
            }
        }


    }

说明：
对于button3_Click，我试图让它调用您设置为保存图像的保存位置。我在网上四处张望，即时通讯找不到解决此问题的方法：/

手动输入保存位置时，也会出现错误。
拒绝访问路径“ H：\ images”。
并且没有文件夹不是只读的。无论我在哪里保存位置，它都会给我同样的错误。

Answer 1

fdb是一个字符串。您已经声明了一个名为字符串类型fdb的类范围的字段，它没有属性SelectedPath

在yout button2_click方法中，您有一个文件对话框，可能您想访问它，因此您需要在类范围的范围内声明它。

private FolderBrowserDialog _fbDlg;
private static string fbd = String.Empty; // Do you really need this?
    public void button2_Click(object sender, EventArgs e)
    {
        _fbDlg = new FolderBrowserDialog();
        _fbDlg.Description = "Select a Folder to save the images.";
        if (_fbDlg.ShowDialog() == System.Windows.Forms.DialogResult.OK)
            textBox1.Text = _fbDlg.SelectedPath;
    }

public void button3_Click(object sender, EventArgs e)
    {

        List<string> address = new List<string>();
        Random r = new Random();
        address.Add("http://d24w6bsrhbeh9d.cloudfront.net/photo/4600000_460s.jpg");
        address.Add("http://d24w6bsrhbeh9d.cloudfront.net/photo/4600001_460s.jpg");
        address.Add("http://d24w6bsrhbeh9d.cloudfront.net/photo/4600002_460s.jpg");
        address.Add("http://d24w6bsrhbeh9d.cloudfront.net/photo/4600003_460s.jpg");
        //MessageBox.Show(address[r.Next(0, 4)]);

        if (comboBox1.Text == "10")
        {
            string filename = _fbDlg.SelectedPath;