Function ValidarCadena(Caractar As Integer, StrValida As String) As Integer
Dim Respuesta As Integer
Respuesta = Caractar
If Caractar > 26 Then
If InStr(StrValida, Chr(Caractar)) = 0 Then
Respuesta = 0
End If
End If
ValidarCadena = Respuesta
End Function
Private Sub txtvalidar_KeyPress(KeyAscii As Integer)
KeyAscii = ValidarCadena(KeyAscii, "01234567ABCDEF")
End Sub