How to delete selected row of data in list box and update the relevant text file (remove the same row from the text file) using VB?

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I have tried using the code below, the logic behind it seems to be fine but it does not seem to work once I run the code,it highlights "MyString" and says " variable is used before it has been assigned a value" has anyone got suggestions?Thank you in advance.

What I have tried:

If ListBox1.SelectedItems.Count > 0 Then
           ListBox1.Items.RemoveAt(ListBox1.SelectedIndex)
           Dim MyString As String
           For Count As Integer = 0 To ListBox1.Items.Count - 1
               MyString &= ListBox1.Items.Item(Count) & Environment.NewLine
           Next
           My.Computer.FileSystem.WriteAllText("Z:\Desktop\ciao.txt", MyString, False)
       End If
   End Sub

Posted 15-Feb-18 4:45am

faiqaa

Updated 15-Feb-18 4:53am

v3

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Richard Deeming · Accepted Answer · 2018-02-15T04:53:00

As the error message says, you are reading the value of the variable MyString before the first assignment to it.

Firstly, if there are no items left in ListBox1, the code inside your loop will never execute. When you come to the WriteAllText line, the variable has not had a value assigned to it.

Secondly, inside the loop, you're appending a string to the variable. But that involves reading the current value of the variable first. On the first iteration of the loop, no value has been assigned.

The quick fix is to assign a value before the loop:

VB.NET

Dim MyString As String = ""

However, it's generally a good idea to avoid string concatenation in a loop. Depending on the number of items in your list, you might want to loop at using a StringBuilder[^] to build the string.