B4J Code Snippet AlphaCountUp - Counts up serialnumbers

This function counts up alphanumeric values. This is necessary, for example, for serial-number generation.
You can change the order and chars in your choice with the 'Values' variable.

'This function counts up alphanumeric values. This is necessary, for example, 
'for serial-number generation.
'You can change the order and chars in your choice with the 'Values' variable.
'AlphaCountUp( "123AZ") > 123B0
Sub AlphaCountUp( StartValue As String) As String
    'according to an idea by
    'https://activevb.de/tipps/vb6tipps/tipp0522.html
    Dim Values As String =  "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    Dim ReturnValue As String = ""
    Dim NextUp As Boolean = True    ' Starts with true = +1
    StartValue = StartValue.Trim.ToUpperCase
   
    ' Check valid Input
    For i=0 To StartValue.Length -1
        If Values.IndexOf( StartValue.CharAt(i)) = -1 Then
            LogDebug( "no valid StartValue "& i &" "& StartValue.CharAt(i))
            Return ""
        End If
    Next
   
    For i=StartValue.Length -1 To 0 Step -1   
        Dim c As String = StartValue.CharAt( i)
        Dim p As Int = Values.IndexOf( c)
       
        If NextUp Then
            p = p +1
            NextUp = False
        End If
       
        If p > Values.Length -1 Then
            ' like 109 -> 110
            ReturnValue = Values.CharAt( 0) & ReturnValue
            NextUp = True
        Else
            ReturnValue = Values.CharAt( p) & ReturnValue
        End If
    Next
   
    ' one digit more like 99 -> 100
    If NextUp Then ReturnValue = Values.CharAt(1) & ReturnValue
'    Log( TAB& StartValue)
'    Log( TAB& ReturnValue)
    Return ReturnValue
End Sub