How to check for date range overlapping another list of date ranges

HCL Domino Domino Forum
1

Hi,

If I have a date range (StartDate-EndDate), how can I tell if this date overlaps a list of other date ranges ie (StartDate1-EndDate1; StartDate3-EndDate3; StartDate3-EndDate3;…).

This is for a scheduling type app.

Any ideas?

THX, Tony

2

Subject: How to check for date range overlapping another list of date ranges

create 3 ranges on a piece of paper and see how you as a person will solve it

Then code it.

3

Subject: RE: How to check for date range overlapping another list of date ranges

Well, OK but this will be open ended so I need to take into account n ranges.

4

Subject: RE: How to check for date range overlapping another list of date ranges

You’ll need to expand on that generallization. Do you mean …

1 - Given n date-ranges, do they ALL overlap ? (i.e. There is at least one date common to ALL of them)

or

2 - Given n date-ranges, do ANY overlap ? (i.e. There is at least one date common to 2 of them)

5

Subject: RE: How to check for date range overlapping another list of date ranges

Hi Graham, I mean option 2.

That is given Range A, does it overlap any of the dates in Range (B, C, D, …n) . (B, C, D…n) are all discrete and should have no overlaps.

6

Subject: RE: How to check for date range overlapping another list of date ranges

Then the logic is …

For each range X in (B…n) to be checked.

If End(A) < Start(X) or End(X) < Start(A)

then

A and B are distinct. - Check next range

else

There is an overlap

7

Subject: RE: How to check for date range overlapping another list of date ranges

One way to code this is …

Dim sess As New NotesSession, ws As New NotesUIWorkspace, uidoc As NotesUIDocument

Dim startDate1 As NotesDateTime, endDate1 As NotesDateTime

Dim startDate2 As NotesDateTime, endDate2 As NotesDateTime

Dim item As NotesItem, range() As String, i As Integer, k As Integer, overlap As Boolean, result As Boolean



'Initialize the variables

i = 0	

result = False

Set uidoc = ws.CurrentDocument

Set item = uidoc.Document.GetFirstItem("DatesToUse")	



'Check the dates	

Forall dt In item.Values

	Redim Preserve range(i)

	range(i)= Cstr(dt)	

	If i>0 Then

		   Set startDate1 = sess.CreateDateTime(Strleft(range(i),"-"))

		   Set endDate1 = sess.CreateDateTime(Strright(range(i),"-"))	

		   For k = 0 To i-1

			   overlap = True

			   Set startDate2 = sess.CreateDateTime(Strleft(range(k),"-"))

			   Set endDate2 = sess.CreateDateTime(Strright(range(k),"-"))

			   If startDate1.TimeDifferenceDouble(endDate2)>0 Or startDate2.TimeDifference(endDate1)>0 Then overlap = False

			   If overlap = True Then result = True

		Next

	End If

	i=i+1

End Forall



'Return the result

Call uidoc.FieldSetText("Overlap",Cstr(result))

Here the code is in a button that reads from a multivalue text field called DatesToUse that contains entries in the form of mm/dd/yy-mm/dd/yy and places the result in a text field called Overlap.