StreamWriter randomly not outputting last line into file

Question

I'm trying to save a class to a text file and I'm getting mixed results. Half the time the last line of the add is in the file and sometimes not. I've not been able to get a consistent output to the file.

So, I added a debug to show me what was being written just prior to the StreamWriter.Write and it showed the line that I added but it doesn't show up in the file.

^ This line is the last line that isn't being written to the file.

Here's what my code where I save the data looks like:

  Private sub SaveMemoUsersFile()

      If _memoList is Nothing Then
        return
      End If

      Dim memofile = Path.Combine(Configuration.DataFileLocations, $"{Configuration.CompanyID}ucMemoUsers.txt")
      Const quote As String = """"
      Const comma As String = ","
      Dim both = $"{quote}{comma}{quote}"

      Using sw = New StreamWriter(memofile)
        For Each memoUsers As MemoUsers In _memoList
          Dim sb = New StringBuilder()
          sb.Append(quote)
          sb.Append(memoUsers.Initials)
          sb.Append(both)
          sb.Append(memoUsers.EmailAddress)
          sb.Append(both)
          sb.Append(memoUsers.DelinquentLetterCode)
          sb.Append(both)
          sb.Append(memoUsers.Description)
          sb.Append(quote)
          'sb.Append(vbCr)
          console.write(sb) <--- shows the last line
          sw.WriteLine(sb.ToString()) <--- but doesn't write it to the file
        Next
      End Using

    _memoList = nothing

  End sub

Anyone have any suggestions? I'm completely lost as to why this is writing to the file randomly.

Flush it? Why do you have `vbCr` instead of `vbCrLf` or `vbLf` or `sw.Writeline()`? Nobody uses char 13 as line separator anymore. — Jimi, Oct 12 '20 at 15:59
I changed that but it didn't have any affect on the save. It's still doing the same thing. Shouldn't the using handle the fush? — ErocM, Oct 12 '20 at 16:20
I hear ya. I just had my question closed because someone who was unfamiliar with the particular technology didn't understand my question said I needed to add detail. The detail was there... Any further detail would have been irrelevant and distracting. To YOUR question I wish I had an answer but it does seem related to the presence/absence of of CR, LF, or CRLF, or none of the above. (The last line often has nothing, which looks fine to humans but not to software looking for a "complete" line.) — PaulOTron2000, Oct 12 '20 at 16:45
It may depend on the context of the operations. `_memoList` is not passed as argument to the method, difficult to say how it's used and what uses it (or *when*). This method is out of context: it could be run on a thread, it's not clear what kind of application this is (thus the *general Context*). I'd remove that `_memoList = nothing`, move the StringBuilder declaration before the loop and `.Clear()` it after the content has been written. Flush after the loop. -- I could probably agree that clarifications could have been asked before downvoting, but is it that important? — Jimi, Oct 12 '20 at 16:59

score 0 · Answer 1 · answered Oct 12 '20 at 16:41

Might as well just build your file in the stringbuilder and write it:

Private sub SaveMemoUsersFile()

      If _memoList is Nothing Then
        return
      End If

      
      Dim q = """"
      Dim b = $"{q},{q}"

      Dim sb = New StringBuilder()

      For Each memoUsers As MemoUsers In _memoList
          sb.Append(q)
          sb.Append(memoUsers.Initials).Append(b)
          sb.Append(memoUsers.EmailAddress).Append(b)
          sb.Append(memoUsers.DelinquentLetterCode).Append(b)
          sb.Append(memoUsers.Description).AppendLine(q)
      Next

      Dim memofile = Path.Combine(Configuration.DataFileLocations, $"{Configuration.CompanyID}ucMemoUsers.txt")
     
      IO.File.WriteAllText(memoFIle, sb.ToString())

      _memoList = nothing

  End sub

Thank you! I've learned something today! I'll clean up my code although changing it to WriteAllText didn't solve my problem. Starting to think it's the class I'm bound to. — ErocM, Oct 12 '20 at 17:15
WriteAllText is definitely reliable, and if your stringbuilder contains the text the file will too; use the debugger to verify the contents of the stringbuilder — Caius Jard, Oct 12 '20 at 19:49

StreamWriter randomly not outputting last line into file

1 Answers1