How to catch FtpWebResponse exception in C #

Question

I am creating an FTP utility class in C #. In the case when a WebException throws a call to FtpWebRequest.GetResponse() , in my case an exception is thrown for the requested file that does not exist on the remote server, the FtpWebResponse variable is out of scope.

But even if I declare a variable outside the try..catch block, I get a compilation error: "Using an unrecognized local variable" answer "", but as far as I can tell, there is no way to assign it until you assign the answer through the FtpWebRequest.GetResponse()

Can someone consult, or am I missing something obvious?

Thanks!

Here is my current method:

 private void Download(string ftpServer, string ftpPath, string ftpFileName, string localPath, string localFileName, string ftpUserID, string ftpPassword) { FtpWebRequest reqFTP; FtpWebResponse response; try { reqFTP = (FtpWebRequest)FtpWebRequest.Create(new Uri("ftp://" + ftpServer + "/" + ftpPath + "/" + ftpFileName)); reqFTP.Method = WebRequestMethods.Ftp.DownloadFile; reqFTP.UseBinary = true; reqFTP.Credentials = new NetworkCredential(ftpUserID, ftpPassword); /* HERE IS WHERE THE EXCEPTION IS THROWN FOR FILE NOT AVAILABLE*/ response = (FtpWebResponse)reqFTP.GetResponse(); Stream ftpStream = response.GetResponseStream(); FileStream outputStream = new FileStream(localPath + "\\" + localFileName, FileMode.Create); long cl = response.ContentLength; int bufferSize = 2048; int readCount; byte[] buffer = new byte[bufferSize]; readCount = ftpStream.Read(buffer, 0, bufferSize); while (readCount > 0) { outputStream.Write(buffer, 0, readCount); readCount = ftpStream.Read(buffer, 0, bufferSize); } ftpStream.Close(); outputStream.Close(); response.Close(); } catch (WebException webex) { /*HERE THE response VARIABLE IS UNASSIGNED*/ if (response.StatusCode == FtpStatusCode.ActionNotTakenFileUnavailable) { //do something } } 

Answer 1

As a general way to resolve this question, first assign a null answer first, and then check the catch block if it is null .

  FtpWebResponse response = null; try { ... } catch (WebException webex) { if ((response != null) && (response.StatusCode == FtpStatusCode.ActionNotTakenFileUnavailable)) { //do something } } 

However, in this particular case, you have all the necessary properties in the WebException instance (including the server response )!

Answer 2

In this question, you can find the correct solution to the problem:
How to check if a file exists on FTP before FtpWebRequest

In short:
Due to an error, your response variable will always be zero. You need to test the FtpWebResponse from "webex.Response" (drop it) to get the StatusCode.

Answer 3

Well, you can always assign a variable:

 FtpWebRequest reqFTP = null; FtpWebResponse response = null;