Attribute VB_Name = "Module1"

Private Function PvmOK(ByVal PvmKokeilu As Variant) As Boolean
  Dim TmpB As Boolean
  TmpB = False
  If IsEmpty(PvmKokeilu) Then
    TmpB = False
  Else
    If IsDate(PvmKokeilu) Then
      TmpB = True
    Else
      TmpB = False
    End If
  End If
  PvmOK = TmpB
End Function


Private Function KerroinOK(ByVal KerroinKokeilu As Variant, _
                            ByVal TyhjaArvoNollaksi As Boolean) As Boolean
  Dim TmpB As Boolean
  If IsEmpty(KerroinKokeilu) Then
    If TyhjaArvoNollaksi Then
      TmpB = True
    Else
      TmpB = False
    End If
  Else
    If IsNumeric(KerroinKokeilu) Then
      TmpB = True
    Else
      TmpB = False
    End If
  End If
  KerroinOK = TmpB
End Function

Private Function Tarkistukset()
  Dim ArvoPvm As Variant
  Dim ArvoLuku As Variant
  Dim TmpB As Boolean
  TmpB = True
  ArvoPvm = ThisWorkbook.Sheets(1).Range("A1").Value
  ArvoLuku = ThisWorkbook.Sheets(1).Range("B1").Value
  If Not PvmOK(ArvoPvm) Then TmpB = False
  If Not KerroinOK(ArvoLuku, False) Then TmpB = False
  Tarkistukset = TmpB
End Function

Private Sub Laskenta()
  MsgBox "Tarkistukset oikein, aloitetaan laskenta"
End Sub

Public Sub Main()
  If Tarkistukset Then Laskenta
End Sub