Program works but ends with error.

dahermit · #1 (**permalink**) March 7th, 2012, 04:02 PM

I am using VB 2010 Express, Win7.
I am a 68 year old retired school teacher who has not programmed for over six years...last was VB 2. I am trying to write code to upgrade a former progam but have run into trouble. As the title says, the program segment works, but ends with the following errors:

Quote:

Argument out of range exception was unhandled.
Index and Length must refer to a location within the string. Parameter name: Length.
Trouble shooting tips:
Make sure the arguments to this method have valid values.

The Code:

Quote:

Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click
'Declares a Numeric Variable.
Dim N As Integer
' Returns the length of the string in the Text Box assigns it to "N".
N = Len(TextBox1.Text)
' Declares an Array to hold String data, adjusting string lenght for 0-9.
Dim SecretinPut(N - 1) As String

For Index As Integer = 0 To N
' "Index" will start with the first char. of the first word, store in Array
SecretinPut(Index) = (TextBox1.Text.Substring(Index, 1))
' Just to keep track of values...puts in a message box on screen as pgm. runs.

MessageBox.Show(SecretinPut(Index))
'Output to a diskfile, appends anything already there.
My.Computer.FileSystem.WriteAllText("C:\Holding.tx t", SecretinPut(Index), True)

Next Index

End Sub

Private Sub TextBox1_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TextBox1.TextChanged

End Sub
End Class

The red font indicates the code that generates the error.

Can anyone tell me what is wrong/how to fix it?

Apocolypse2005 · #2 (**permalink**) March 7th, 2012, 06:50 PM

This is a simpler way of doing. Lists are better to use than arrays, especially typed ones. Nicer to look at, more semantic.

Code:

Dim arrayChar As List(string)

For i as Integer = 0 to Textbox1.text.length

    arrayChar.add(Textbox1.text.substring(i, 1))
    Messagebox.show(arrayChar.Item(i).ToString)

Next

'Doing the file writing after, means that if you do hit an error, its not left up to garbage collector to do the work, ideally you don't want the file open cause this will cause errors in the disk obviously. Better to do it separately so it can be handle properly

'use a few try catch statements for extra safety if necessary

Dim p As New FileStream("C:\NewText.txt", {and the appropriate write flags, don't know them off the top of my head})
Dim pt As New TextWriter(p)

For each charString In arrayChar

    pt.writeline(charString)

next

pt.close 'this flushes the file so writes to disk

dahermit · #3 (**permalink**) March 7th, 2012, 09:20 PM

Thank you for you code suggestions.
I am more comfortable with using arrays for a few reasons. I am more familiar with them, only having heard of lists a week or so ago when I bought my first VB 2010 books. Also, arrays seem to be more adept at manipulation via For/Next loops (Is that true?). The program segment I listed above does not fore tell the manipulation of the characters that will occur further in the program and at his point I am still struggling with the VB 2010 language and want to just get the program working; not so much concerned with the elegance of the coding. I am discovering that VB 2010 is several times more complicated than VB 2, QBASIC, Pascale et. Al., were. I feel sorry for those who have to learn it as their first programming language.
Thank you again for your help.

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