[RESOLVED] Crash when overwriting using StreamWriter.

[EntityX]

I'm getting a problem when writing text files using StreamWriter. The files read fine and they write fine if I'm not overwriting an existing file. They also write ok as long as I'm not writing over a file that only has one digit at the end of the name. For some reason when there are 2 digits at the end it crashes when I'm trying to save over an already existing text file. Here's my code.

      StringForTextFile = "C:\" & Folder4PS & "\" & IDCodewDashOrN & "Series" & Series & "ScreenNumber" & ScreenNumber & ".txt"
        LblTesting.Visible = True ' Testing
        LblTesting.Text = "StringForTextFile = " & StringForTextFile
        If File.Exists(StringForTextFile) = True Then
            Dim PerScrnsData As StreamWriter '                 False becasue will overwrite over already existing file
            PerScrnsData = New StreamWriter(StringForTextFile, False, Encoding.UTF8) '
            AcceptSettings()
            PerScrnsData.Write(PersonalScreensDataToStringAll())
            PerScrnsData.Close()
        Else
            Dim PerScrnsData As StreamWriter '                 True because will write new file that doesn't exist
            PerScrnsData = New StreamWriter(StringForTextFile, True, Encoding.UTF8) '
            AcceptSettings()
            PerScrnsData.Write(PersonalScreensDataToStringAll())
            PerScrnsData.Close()
        End If

I have PerScrnsData = New StreamWriter(StringForTextFile, False, Encoding.UTF8) above but 've tried all the different Encoding possibilites. Unicode, UTF32, UTF8, UTF7 as well as without those parameters listed where the close parentheses is right after StringForTextFile. I get the same result. If I'm writing a new text file that doesn't exist, then no problem or if I'm writing over an existing text file but it has 0 to 9 at the end then I'm ok but if I'm writing over an existing file and there is 10 or above(haven't tried triple digits or all values) then my application crashes. You see the test label in the code above because I was looking at exactly what file it was trying to overwrite and it is just as it should be.

Should I be using a different procedure? An example of a string that would cause a crash for the string StringForTextFile would be :

C:\Name of My App\Series1ScreenNumber10.txt

If it was being written for the first time then no problem or if the 10 at the end was 0 to 9 then no problem also.

I've also tried and originally had it set up where there wasn't an If File.Exists(StringForTextFile) = True Then statement. It just always used the same code whether writing or overwriting and I wasn't having a problem that I remember. For some reason I started having a problem recently and I put the alternate methods of writing in.

[EntityX]

I just thought of something simple. Just delete the file first if it already exists and then write it new. I'll look into how to delete the file if it already exists.

[EntityX]

Very simple indeed. If file already exists then :

 My.Computer.FileSystem.DeleteFile(StringForTextFile)

If someone knows why it was only having a problem overwriting with 10 or above at the end that might be interesting to know why. You just need one good way to fix a problem.

Thank you EntityX for solving my problem. You're welcome.

[jmcilhinney]

If it crashes then it gives you an error message. If you'd like us to help you fix the problem then we shouldn't really have to ask for you to tell us what it is.

Apart from that, if you want to overwrite an existing file then differentiating between a new and existing file is unnecessary. Did you read the documentation for the StreamWriter constructor?

If the file exists and append is false, the file is overwritten. If the file exists and append is true, the data is appended to the file. Otherwise, a new file is created.

If there's no existing file then a file gets created either way, so forget checking and just set append to False.

[EntityX]

I was trying both ways and it was crashing. I turned unmanaged code debugging on. Before I did that it would show me the problem line but not any message.

If I put the code back like it was before, I get this message:

An unhandled exception of type 'System.UnauthorizedAccessException' occurred in mscorlib.dll

Additional information: Access to the path 'C:\Ray Rover Personal Screens\Series1ScreenNumber10.txt' is denied.

Deleting the file if it exists works just fine but why would it only have this problem if the file already exists and the number at the end is 10 or above. There's no problem if there is 0 to 9 at the end.

Here's the code I'm using now that solves my problem.

    StringForTextFile = "C:\" & Folder4PS & "\" & IDCodewDashOrN & "Series" & Series & "ScreenNumber" & ScreenNumber & ".txt"
        If File.Exists(StringForTextFile) = True Then
            My.Computer.FileSystem.DeleteFile(StringForTextFile)
        End If
        Dim PerScrnsData As StreamWriter
        PerScrnsData = New StreamWriter(StringForTextFile, False, Encoding.Unicode) '
        AcceptSettings()
        PerScrnsData.Write(PersonalScreensDataToStringAll())
        PerScrnsData.Close()

[jmcilhinney]

I don't know the answer to that and I haven't tested it but, on an unrelated note, you should start using the String.Format method:

StringForTextFile = String.Format("C:\{0}\{1}Series{2}ScreenNumber{3}.txt", _
                                  Folder4PS, _
                                  IDCodewDashOrN, _
                                  Series, _
                                  ScreenNumber)

That's far easier to read and, therefore, far less error-prone.