Read the correct week number from a calendar date - vba

Question

I have below dates in an Excel column, as you can see.
Sprint 1 takes from 10.04 to 21.04 this means 2 weeks and between brackets they are specified week 15 and 16 which is correct but for Sprint 2, who also starts in 10.04 but takes until 05.05 it means 7 weeks, but are displayed also the weeks from the Sprint1.
"Sprint1 (CW15-16/2017)
[10.04.2017 - 21.04.2017]
Sprint2 (CW15-16/2017)
[10.04.2017 - 05.05.2017]"
What I have until now is:
'reading the first CW of the sprint based on the date
SprintFristCW = Left(planning_wb.Worksheets(SprintPlanningTable).Cells(2, i + 1).Value, 9)
'reading the last CW of the Sprint based on the date
SprintEndCW = Right(planning_wb.Worksheets(SprintPlanningTable).Cells(2, i + Sprintlength).Value, 9)
SprintCW = Left(SprintFirstCW, 4) & "-" & Right(SprintEndCW, 7)
But SprintEndCW is not reading correct the week number.
So I need to read the correct week number in which each sprint ends and print it.

Answer 1

Don't create huge procedures. Small is beautiful. Create functions that feed into your Main procedure. Here is an example. The procedure TestExtraction calls the function ExtractWeeks. Therefore ExtractWeeks needs not be part of the procedure that calls it, making the code easier to understand and maintain.
Private Sub TestExtraction()
Dim Fun As Long
Dim DateString As String
Dim StartDate As Date, EndDate As Date
DateString = ActiveCell.Value
' the DateString is re-defined here for testing purposes
DateString = "[10.04.2017 - 05.05.2017]"
Fun = ExtractWeeks(DateString, StartDate, EndDate)
If Fun < 0 Then
Debug.Print "Invalid date"
Else
With Application
DateString = "(CW" & .WeekNum(StartDate)
If Year(StartDate) <> Year(EndDate) Then _
DateString = DateString & "/" & Year(StartDate)
DateString = DateString & " - " & .WeekNum(EndDate) & "/" & Year(EndDate) & ")"
End With
Debug.Print DateString
Debug.Print Fun & " weeks"
End If
End Sub
Private Function ExtractWeeks(ByVal DateString As String, _
StartDate As Date, _
EndDate As Date) As Long
' 24 Oct 2017
' return the number of weeks between dates (rounded up)
' return -1 if one of the dates is unreadable
Dim Dates() As String
Dim i As Integer
Dates = Split(Mid(DateString, 2, Len(DateString) - 2), "-")
On Error Resume Next
For i = 0 To 1
Dates(i) = Replace(Trim(Dates(i)), ".", Application.International(xlDateSeparator))
Next i
StartDate = DateValue(Dates(0))
EndDate = DateValue(Dates(1))
If Err Then
ExtractWeeks = -1
Else
ExtractWeeks = Int((StartDate - EndDate) / 7) * -1
End If
End Function
The point is that not everything that looks like a date is a date Excel can understand. The Function ExtractWeeks converts the "dates' from your worksheet into real dates and returns these dates to the calling procedure. It also returns -1 in case of error which you can use to trap such errors. In my example, the function returns the number of weeks (or -1). You might let it return the CW string my calling procedure constructs. You will find it easy to move the process of constructing that string to the function and let the function return "" in case of error instead of -1. Perhaps you can exclude the possibility of errors in the dates. This is a question of how you integrate the function into your Main.