Parse international standard date & time notation

[Merri]

Just in case someone wonders why I don't use the DatePart function for week numbers, I noticed that it gives incorrect results.

Option Explicit

Private Sub Form_Load()
    Dim intYear As Integer
    For intYear = 2000 To 2010
        Debug.Print DateSerial(intYear, 13, 0), IWeek(DateSerial(intYear, 13, 0)), DatePart("WW", DateSerial(intYear, 13, 0), vbMonday, vbFirstFourDays)
    Next
End Sub

31.12.2000    2000-W52-7     52 
31.12.2001    2002-W01-1     1 
31.12.2002    2003-W01-2     1 
31.12.2003    2004-W01-3     1 
31.12.2004    2004-W53-5     53 
31.12.2005    2005-W52-6     52 
31.12.2006    2006-W52-7     52 
31.12.2007    2008-W01-1     53 
31.12.2008    2009-W01-3     1 
31.12.2009    2009-W53-4     53 
31.12.2010    2010-W52-5     52

So that is why I had to write a "cumbersome" week numbering math. But as far as I can see it works correctly