在VB.NET中如何确定两个日期之间的天数

Private Sub DetermineNumberofDays()


        Dim dtStartDate As Date = "1/1/2007"
        Dim tsTimeSpan As TimeSpan
        Dim iNumberOfDays As Integer
        Dim strMsgText As String


        tsTimeSpan = Now.Subtract(dtStartDate)


        iNumberOfDays = tsTimeSpan.Days
        strMsgText = "The total number of days elapsed since " & dtStartDate.ToShortDateString() & " is: " & iNumberOfDays.ToString()
        MsgBox(strMsgText)


    End Sub