VB.Net MultiLine Text Boxes

Here is my problem, i have a multi line Text Box and a List Box on my form.
The user can copy and paste a List of numbers in the multi line text Box.
When he clicks on Process i want to read line for line from text box and then
do some validation and if successful move the item to list box and remove from
text box.
I have my code who does the validation and putting int into the list box,, but having
issues with the removing from text box.

I tried to load the lines into a string list and then remove from string but problem
is that if i remove the item the list no longer has the same count as when i start and
the system will complain index out of range

Any ideas how to solve this cleanly ?
AlexPonnathAsked:
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Fernando SotoConnect With a Mentor RetiredCommented:
Hi Alex;

Try this modified version of your code. It should do what you need.
If txtNumbers.Lines.Count > 0 Then
    Dim newList As List(Of String) = txtNumbers.Lines.ToList
    '' Access the newList in reverse order so that deleted items do not effect un-processed items
    '' by having its index changed and therefor changing all other item index
    For i As Int32 = newList.Count - 1 To 0 Step -1
        '' Because items are being inserted in reverse order use the Insert methods in place of
        '' The Add method and always Insert at index zero.
        lbNumbers.Items.Insert(0, newList.Item(i))
        'Remove the first line.  
        newList.RemoveAt(i)
    Next
    '' Now seeming you are working with a copy of the Items in the TextBox you need to place the 
    '' Items that were not removed back in the TextBox
    txtNumbers.Lines = newList.ToArray
End If

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Fernando SotoRetiredCommented:
Can you show your code and how you manipulate the lines in the TextBox? Are you using the Lines collection?
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AlexPonnathAuthor Commented:
If txtNumbers.Lines.Count > 0 Then
            Dim newList As List(Of String) = txtNumbers.Lines.ToList
            For i As Int32 = 0 To newList.Count - 1

                lbNumbers.Items.Add(AddPhoneFormat(newList.Item(i)))
                ' Remove the first line.  
                'newList.RemoveAt(i)

            Next
        End If

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