Question Global array problem

[ucp8]

Hi,

I am developing a piece of software using VB.NET which allows teachers to test and monitor their students progress. The problem I am facing is that I am using a Module to hold the questions array variable:

Friend Questions() As String

When I attempt to apply a value to each of the array variables, I get the followng error:

Object reference not set to an instance of an object.

I am using the following code to do this:

For k = 0 To 9
Questions(k)=questionDs.Tables("TestQuestions").Rows(k).Item("Question").ToString
Next

I do not understand why it wont apply the values given to it for each of the array variables. If I make Questions() into a standard String using Friend Questions As String , it will apply the value.

I understand that I could create 10 seperate Questions String variables and apply a value to each one but I am trying to cut down on my LOC. Can anyone tell me why I cannot set each array value or how to fix my code to enable this?

 

[ucp8]

After reading my post I found a solution. I noticed that no array size had been set in the variable declaraton. I changed the code in the Module to Friend Questions(10) As String and it worked.

 

[JuggaloBrotha]

For something like this you may want to use a List(Of String) instead of an array

 

[ucp8]

I have never come across Lists, what advantages would they provide over the String array? Thanks for your help

 

[JohnH]

Collections/lists are better used when you need to dynamically add/remove/insert items.

 

[ucp8]

Thanks for the information guys, I'll have a look at them later and see if I can get them working.

 

[MattP]

Friend questions As New List(Of String)

For k As Integer = 0 To 9
     questions.Add(questionDs.Tables("TestQuestions").Rows(k).Item("Question").ToString())
Next