Incrementing Text String

Function IncrementTextString(txt As String) As String
    'taken from http://www.freevbcode.com/ShowCode.asp?ID=2071
    'enhanced to take in numbers also
    Dim L As Integer, i As Integer, c As Integer
    Dim S As String
    S = txt
    L = Len(S)

    For i = L To 1 Step -1    'go thru the string, right to left
        c = Asc(Mid(S, i, 1)) 'ASCII code of the i-th character
        Select Case c
            Case 65 To 89, 97 To 121, 48 To 56  'A-Y or a-y or 0-8
                S = Left(S, i - 1) & Chr(c + 1) & Mid(S, i + 1)
                Exit For
            Case 90    'Z
                S = Left(S, i - 1) & "A" & Mid(S, i + 1)
            Case 122   'z
                S = Left(S, i - 1) & "a" & Mid(S, i + 1)
            Case 57    '0
                S = Left(S, i - 1) & "0" & Mid(S, i + 1)
        End Select
        'in the last two cases, we need to continue the loop:
    Next i
    If i = 0 Then
        IncrementTextString = String(L + 1, 65) 'grow the string
    Else
        IncrementTextString = S
    End If
End Function