[RESOLVED] Parameter name: length

I have never understood these messages so i am attempting to work it out.

Does the below message say that a paremeter in the module LogFile has a zero length?
On my pc clsStream.Write(bFile, 0, bFile.Length) holds values but on 2 w10 pc's this has caused errors.

Code:

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************** Exception Text **************
System.ArgumentOutOfRangeException: Length cannot be less than zero.
Parameter name: length
  at System.String.InternalSubStringWithChecks(Int32 startIndex, Int32 length, Boolean fAlwaysCopy)
  at System.String.Substring(Int32 startIndex, Int32 length)
  at TakeoffExpress.LogFile.gGetInfo()
  at TakeoffExpress.Form1.Form1_Load(Object sender, EventArgs e)
  at System.EventHandler.Invoke(Object sender, EventArgs e)
  at System.Windows.Forms.Form.OnLoad(EventArgs e)
  at System.Windows.Forms.Form.OnCreateControl()
  at System.Windows.Forms.Control.CreateControl(Boolean fIgnoreVisible)
  at System.Windows.Forms.Control.CreateControl()
  at System.Windows.Forms.Control.WmShowWindow(Message& m)
  at System.Windows.Forms.Control.WndProc(Message& m)
  at System.Windows.Forms.ScrollableControl.WndProc(Message& m)
  at System.Windows.Forms.ContainerControl.WndProc(Message& m)
  at System.Windows.Forms.Form.WmShowWindow(Message& m)
  at System.Windows.Forms.Form.WndProc(Message& m)
  at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
  at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
  at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)

---

Code:

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Module LogFile

  Public Sub uUpLoadLogFile()

        'deleted code here to save your eyes

          clsRequest.Method = System.Net.WebRequestMethods.Ftp.AppendFile
            'read into existing log.txt file...
            Dim bFile() As Byte = System.IO.File.ReadAllBytes(My.Computer.FileSystem.SpecialDirectories.MyDocuments & "/TakeoffExpress/Log/Log.txt")
            ' upload file...
            Dim clsStream As System.IO.Stream = clsRequest.GetRequestStream()
            clsStream.Write(bFile, 0, bFile.Length)
            clsStream.Close()
            clsStream.Dispose()

      'deleted code here to save your eyes
  End Sub

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That stack trace is telling you that, in the Load event handler of Form1, you are calling LogFile.gGetInfo and, in that method, you're calling String.Substring and passing a negative number for the 'length' parameter. Obviously you can't get a substring with a negative length. I suggest that you place a breakpoint on that method call in the Load event handler and then you can step to the Substring call and see where that negative length is coming from.

on my pc it hold values and unfortunately i cannot test on the clients pc's so would this work?

in runs though the code fine on my machine....

Code:

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If bFile.Length = 0 Then
            Else
                clsStream.Write(bFile, 0, bFile.Length)
            End If

---

Read my post again and look at the stack trace you posted. That line of code has got exactly zero to do with the issue.

sorted thx.

i have code to count how many times a file is opened each month and on 2 pc's it was causing an error for some reason when it hit a month that has a zero opened times.

I would guess that you were subtracting 1 from that number because indexes are zero-based. In that case, zero opened times would result in an index of -1, which is obviously less than zero and would cause the error message you're seeing.

not sure why it happens on just 2 pc's

this is the code to count the times a jpg is opened....

Code:

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        If lLogOnDate.ToString.Contains("/01/") Then
            My.Settings.jpg_01_Started = My.Settings.jpg_01_Started + 1
        End If
        If lLogOnDate.ToString.Contains("/02/") Then
            My.Settings.jpg_02_Started = My.Settings.jpg_02_Started + 1
        End If
        If lLogOnDate.ToString.Contains("/03/") Then
            My.Settings.jpg_03_Started = My.Settings.jpg_03_Started + 1
        End If
        If lLogOnDate.ToString.Contains("/04/") Then
            My.Settings.jpg_04_Started = My.Settings.jpg_04_Started + 1
        End If
        If lLogOnDate.ToString.Contains("/05/") Then
            My.Settings.jpg_05_Started = My.Settings.jpg_05_Started + 1
        End If
        If lLogOnDate.ToString.Contains("/06/") Then
            My.Settings.jpg_06_Started = My.Settings.jpg_06_Started + 1
        End If

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and this is were the error occurred when adding to a list, writing to a txt file then uploading to a ftp

Attachment 148911

a try catch fixed it...

Don't use an exception handler to catch an exception that you easily prevent in the first place.

You are calling LastIndexOf and then subtracting from the result. LastIndexOf will return -1 if the specified substring is not found and 0 if the last occurrence of the substring is at the beginning of the original string. In either case, the result would be negative and cause the exception you're seeing. The proper course of action would be to validate the input to make sure it conforms to your expectations. If you're expecting a string of a particular minimum length then test the Length of the String to make sure it is at least that much. If you're assuming that a String won't be empty then test that. Etc. Think about what your app requires in order to do what it is supposed to do and then, if those requirements aren't guaranteed to be met, write code to test whether they are or not and proceed according to the result.