Dim Eingabe As String
    Dim i As Integer
    Dim Umkehrung, Rest As String
    Dim txt() As String    
 
Private Sub cmdUmdrehen_Click
        Eingabe = txtEingabe.Text
        ReDim txt(Len(txtEingabe.Text))
        For i = UBound(txt) To LBound(txt) Step -1
            txt(i) = Mid(txtEingabe.Text, i, 1)
            Umkehrung = Umkehrung & txt(i)
            Rest = Umkehrung + Left(txtEingabe.Text, i - 1)
            lstAusgabe.Items.Add(Rest)
        Next i
    End Sub