VB.Net 2005,如何从(当前日期减去7天)中减去日期并生成若干天？

我将来有一个日期,例如13/10/2008我需要减去当前日期(今天是28/09/2010)减去7天,那么21/09/2010减去13/10/2008,这将等于erm,720这个？

但显然,目前的日期并不总是28/09/2010.

我需要这个代码.

编辑：当我说未来我的意思是过去:)

Sub Main()
    Dim dt As DateTime = New DateTime(2008, 10, 13)
    ' be careful what you are subtracting from what
    ' the date you have is not in the future (year 2008)
    ' if the date is in the future: (dt.Subtract(DateTime.Now.AddDays(-7))).TotalDays
    ' or simply take the absolute value
    Dim days As Double = (DateTime.Now.AddDays(-7).Subtract(dt)).TotalDays
    Console.WriteLine(days)
End Sub

您还会注意到TotalDays属性的类型为Double.