Funções usadas no evento KeyPress de um textbox para fazer consistência de dados

Public Function SoNumeroEPonto(ByVal CaracterASCII As Integer) As String
     If (CaracterASCII < 48) Or (CaracterASCII > 57) Then
        If (CaracterASCII <> 46) And (CaracterASCII <> 8) Then
            Return ""
        End If
     End If
     Return Chr(CaracterASCII)
End Function


Public Function SoNumero(ByVal CaracterASCII As Integer) As String
     If (CaracterASCII < 48) Or (CaracterASCII > 57) Then
         If (CaracterASCII <> 8) And (CaracterASCII <> 46) Then
             Return ""
         End If
     End If
     Return Chr(CaracterASCII)
End Function


Public Function SoLetra(ByVal CaracterASCII As Integer) As String
     If (CaracterASCII < 65 Or CaracterASCII > 90) Then
         If (CaracterASCII < 95 Or CaracterASCII > 122) Then
             If CaracterASCII <> 8 Then
                 Return ""
             End If
         End If
     End If
     Return Chr(CaracterASCII)
End Function