Afteller: code

• De klasse
  Public Class afteller
  Dim p_gatot As Date
  Sub New()
  'een lege constructor, omdat er anders alleen een constructor is met paramater
  End Sub

  Sub New(ByVal moment As Date)
  If Now < moment Then
    Err.Raise(100, , "Het moment moet in de toekomst liggen")
    Exit Sub
  End If
  p_gatot = moment
  End Sub

  Public Property moment() As Date
  Get
    Return p_gatot
  End Get
  Set(ByVal Value As Date)
    If Now < moment Then
      Err.Raise(100, , "Het moment moet in de toekomst liggen")
      Exit Property
  End If
  p_gatot = Value
  End Set
  End Property

  Public ReadOnly Property DagenTeGaan() As Long
  Get
    Return DateDiff(DateInterval.Day, Now, p_gatot)
  End Get
  End Property

  Public ReadOnly Property TijdTeGaan() As String
  Get
  Dim uur As Integer = DateDiff(DateInterval.Hour, Now, p_gatot)
  Dim minuut As Integer = DateDiff(DateInterval.Minute, Now, p_gatot)
  Dim seconde As Integer = DateDiff(DateInterval.Second, Now, p_gatot)
  TijdTeGaan = Format(TimeSerial(uur, minuut, seconde), "hh:mm:ss")
  End Get
  End Property
  End Class

• Het formulier
  Dim aft As New afteller
  Private Sub cmdStart_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdStart.Click
  Dim moment As Date
  Dim buffer As Object
  Do
    buffer = InputBox("Tot wanneer moet ik aftellen?")
  Loop Until IsDate(buffer)
  moment = CDate(buffer)
  If Now > moment Then Exit Sub 'niet in het verleden!
    aft.moment = moment
    Timer1.Enabled = True
  End Sub

  Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
  lblDagen.Text = aft.DagenTeGaan.ToString
  lblTijd.Text = aft.TijdTeGaan.ToString
  Text = aft.DagenTeGaan & " dagen en " & aft.TijdTeGaan
  End Sub
  End Class

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