I have a code that loop from A to D and displays the result in a text box as the loop continues.

Dim test(0 To 3) As String

test(0) = "A"
test(1) = "B"
test(2) = "C"
test(3) = "D"

For i As Int32 = 0 To test.Length - 1
TextBox4.Text = test(i)
TextBox4.Refresh()
Me.Refresh()
Next

But the problem is that the loop only goes like A , B , C ,D
How can I make the loop so it keep going on like
A
B
C
D
AA
AB
AC ....and so on?