Error: Object reference not set... (VB)

[VinceC]

Error: Object reference not set...

 

I am using VB.Net (Standard Ed.), my program opens a dialog window for selection of a text file (containing numbers) and reads it in as a "stream". It then tries to convert the stream from text to double (unsuccessfully). The error that I get is on the line of code below where it happens. Here is my code, can someone help?

 

'Code from my Form

       Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click


           Dim OpenFileDialog1 As New OpenFileDialog()
           OpenFileDialog1.InitialDirectory = "c:\"
           OpenFileDialog1.Filter = "txt files (*.txt)|*.txt|All files (*.*)|*.*"
           OpenFileDialog1.FilterIndex = 2

           Dim sreader As IO.StreamReader

           If OpenFileDialog1.ShowDialog() = DialogResult.OK Then
               sreader = IO.File.OpenText(OpenFileDialog1.FileName)
               CreateArray(sreader)
               sreader.Close()
           End If

       End Sub
   End Class

'Code from my Module

   Sub CreateArray(ByVal streamM As IO.StreamReader)

       Dim x As Integer
       Dim q()
       Dim z() As Double
       Dim Efile As String
       Efile = streamM.ReadToEnd
       q = Split(Efile, vbCrLf)

       For x = 1 To q.Length - 1
           z(x) = CDbl(q(x))   'Error I receive: "Object reference not set to an instance of an object."
       Next x
   End Sub

 

Thanks for any help.

Edited June 3, 2003 by divil

[PlausiblyDamp]

Not got VB.Net on the machine in front of me so this hasn't been tested.

 

On the line you are getting the error z(x) probably doesn't point ot a valid array element.

 

a few lines previous you are declaring

Dim z() As Double

 

but at no point are you sizing the array.

 

you may want to try the following and see if it helps

Sub CreateArray(ByVal streamM As IO.StreamReader)

Dim x As Integer
Dim q()
Dim z() As Double
Dim Efile As String
Efile = streamM.ReadToEnd
q = Split(Efile, vbCrLf)

redim z(q.Length - 1)          'Add this line here
For x = 1 To q.Length - 1
z(x) = CDbl(q(x)) 'Error I receive: "Object reference not set to an instance of an object."
Next x
End Sub

[VinceC]

Wow. Thanks for the quick response. It worked. I should have caught that, makes perfect sense. Just starting to use .NET so feeling like a fish out of water.

[Volte]

Also, I feel I must point out the icky-ness of using the 'Split' command,

as it is left over from VB6 for compatability reasons. Instead, the

string commands are actually methods of the String class.

 

in VB6:

Dim a As String
Dim b As String

b = "Hello There!"
a = Split$("Hello There!", " ")

 

in VB.NET:

Dim a, b As String

b = "Hello There!"
a = b.Split(" ")

There is more info about this stuff in the MSDN included with .NET,

or online at http://msdn.microsoft.com.

 

 

 

I recommend you play around with C#, because it forces you to do

things the proper .NET way, taking away those old VB6 commands.

[VinceC]

Thanks for the advice. I'm going to try the .split method you mentioned. I'm also going to start learning a little about C# so that I can gradually make the transition from VB.NET. After reading a few posts here and there it seems C# is the better way to go?