Visual Basic Beginner ..SubStrings - vb.net

Question

I'm new to programming and I'm trying to figure out this simple question! The language is Visual Basic! The Question is below:
"Users of a computer program often like to enter numbers with commas inserted in the middle, such as "1,234,000,688". Most computer languages consider this format to be non numeric. Write a program that inputs a number containing no more than three commas, and produces a string containing the same number without the commas"
When I enter this number: 1,234,000,688 and hit Display in Visual Basic I get this error message --> Argument is out of range Exception was unhanded
I'm not exactly sure why this is happening because I'm within my strUserInput length.
My Code:
Public Class Form1
Private Sub btnDisplay_Click(sender As Object, e As EventArgs) Handles btnDisplay.Click
'Variable declarations
Dim strUserInput = txtUserInput.Text
Dim strOutputNumber1 As String
Dim strOutputNumber2 As String
Dim strOutputNumber3 As String
Dim strOutputNumber4 As String
' 1,234,000,688
strOutputNumber1 = strUserInput.Substring(0, 1)
strOutputNumber2 = strUserInput.Substring(2, 4)
strOutputNumber3 = strUserInput.Substring(5, 8)
strOutputNumber4 = strUserInput.Substring(9, 12)
lblDisplayNumber.Text = strOutputNumber1 & strOutputNumber2 & strOutputNumber3 & strOutputNumber4
End Sub
Private Sub btnExit_Click(sender As Object, e As EventArgs) Handles btnExit.Click
Me.Close()
End Sub
Private Sub btnClear_Click(sender As Object, e As EventArgs) Handles btnClear.Click
lblDisplayNumber.Text = String.Empty
txtUserInput.Text = String.Empty
End Sub
End Class

Answer 1

You're getting that exception because of the way you're using substring, the last one there starts at index 9 and extends 12 characters...that would be a 22 character number, and the text you have as input is probably much shorter. You don't need to make things overly complicated for yourself using substrings, all of the above code could be greatly condensed and cleaned up by simply using String.Replace like this:
Public Class Form1
Private Sub btnDisplay_Click(sender As Object, e As EventArgs) Handles btnDisplay.Click
lblDisplayNumber.Text = txtUserInput.Text.Replace(",", "")
End Sub
Private Sub btnExit_Click(sender As Object, e As EventArgs) Handles btnExit.Click
Me.Close()
End Sub
Private Sub btnClear_Click(sender As Object, e As EventArgs) Handles btnClear.Click
lblDisplayNumber.Text = String.Empty
txtUserInput.Text = String.Empty
End Sub
End Class