Check if two ranges of dates overlap [Excel Formulas]

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Check if two ranges of dates overlap using excel formulasWhile preparing a project plan, I had a strange problem. I wanted to highlight all the project tasks that fall with-in a certain date range. At the lowest level, the problem is like this:

There are 2 ranges of dates (a,b) and (x,y) and I want to know if they overlap (ie at least one date common between a,b and x,y)

The formula for testing such a thing seemed tricky at first. So I drew the conditions on paper to get clarity on what we should test. Evidently, there are 4 ways in dates (a,b) can overlap with dates (x,y) as shown below:

Conditions to check if two sets of dates overlap

Now, we can test for the overlap condition using a formula like this:

If x is between a and b
or a is between x and y
then overlap
else do not overlap

As you know, there is no formula in excel like isbetween(). So we have to break it up to 2 conditions and an AND() Formula. Finally the formula becomes,

=if(or(and(x>=a,x<=b),and(a>=x,a<=y)),"Overlap","Do not overlap")

Now, it seemed like quite a big formula for testing if 2 ranges of dates overlap.

So, I continued my quest for even shorter formula.

After sometime, I realized that if we test for non-overlap instead of overlap, we can write a shorter formula.

Do not understand? Let me explain.

While there are 4 ways in which (a,b) can overlap with (x,y), there are only two ways in which (a,b) cannot overlap with (x,y). See this to understand:

Conditions to check if two sets of dates do NOT overlap

Now, testing above conditions is very straight forward in excel.

the formula becomes, =if(or(y<a,b<x),"Do not overlap","Overlap")

The formula is much shorter and easy to maintain.

I was able to use it to test if a set of tasks in the project plan are running between given dates (for eg. next week). All is well in the end.

How do you test overlap conditions?

Do you ever have to test overlap conditions? What kind of formulas have you used? Please share your formula tips & tricks using comments.

Further Learning:

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26 Responses to “Get busy this weekend, with OR XOR AND [Excel Homework]”

  1. Stef@n says:

    first solution for AND
    The two numbers are in A1 and B1
    = SUBSTITUTE (SUBSTITUTE (A1+B1*9*9, 9, 1), 8, 0)
    regards
    Stef@n

  2. Stef@n says:

    next solution for OR
    =1*SUBSTITUTE (A1+A2;2;1)

    regards
    Stef@n

  3. Stef@n says:

    last solution for XOR
    =1*SUBSTITUTE (A1+A2;2;0)

    regards
    Stef@n

  4. Irvine says:

    Or you could make use of the VBA logical operators!

    Define the following as custom functions
    Public Function BITXOR(x As Long, y As Long)
    BITXOR = x Xor y
    End Function

    Public Function BITAND(x As Long, y As Long)
    BITAND = x And y
    End Function

    Public Function BITOR(x As Long, y As Long)
    BITOR = x Or y
    End Function

    and then use them such:
    A B =BITOR(A,B) =BITAND(A,B) =BITXOR(A,B)
    0101 0100 0101 0100 0001

  5. Stef@n says:

    an another solution for AND
    =1*SUBSTITUTE (SUBSTITUTE (A1+A2;1;0);2;1)

    note:
    the binary numbers are in A1 and A2 !
    regards
    Stef@n

  6. Shair says:

    I was obviously playing hooky at the beach during the bit-wise math lesson – you lost me at “Understanding bit-wise operations” 🙂

  7. Anup Agarwal says:

    After looking at the above solutions, I find my solution silly, but still:

    For the following formulae,
    Row 1: headers,
    Row 2: OR
    Row 3: AND
    Row 4: XOR

    Column 1: Input 1
    Column 2: Input 2
    Column 3: Result

    OR
    {=SUM(IF(MID(A2,ROW(OFFSET($A$1,0,0,LEN(A2),1)),1)+MID(B2,ROW(OFFSET($A$1,0,0,LEN(B2),1)),1)>0,1,0)*10^(LEN(A2)-ROW(OFFSET($A$1,0,0,LEN(B2),1))))}

    AND
    {=SUM(IF(MID(A3,ROW(OFFSET($A$1,0,0,LEN(A3),1)),1)+MID(B3,ROW(OFFSET($A$1,0,0,LEN(B3),1)),1)=2,1,0)*10^(LEN(A3)-ROW(OFFSET($A$1,0,0,LEN(B3),1))))}

    XOR
    {=SUM(IF(MID(A4,ROW(OFFSET($A$1,0,0,LEN(A4),1)),1)+MID(B4,ROW(OFFSET($A$1,0,0,LEN(B4),1)),1)=1,1,0)*10^(LEN(A4)-ROW(OFFSET($A$1,0,0,LEN(B4),1))))}

  8. Hui... says:

    @Anup
    Please don't consider your solution silly
    Firstly, You are the 3rd person to submit an answer
    Secondly, The best formula/function is the one that you know and understand.

  9. Michael Azer says:

    I think I have a very tedious solution, which people won't have the patience to do except in small numbers.

    I used the same problem setup as "Anup Agarwal"

    AND =IF(AND(MID(B2,1,1)="1",MID(C2,1,1)="1"),1,0)&IF(AND(MID(B2,2,1)="1",MID(C2,2,1)="1"),1,0)&IF(AND(MID(B2,3,1)="1",MID(C2,3,1)="1"),1,0)&IF(AND(MID(B2,4,1)="1",MID(C2,4,1)="1"),1,0)

    OR =IF(OR(MID(B3,1,1)="1",MID(C3,1,1)="1"),1,0)&IF(OR(MID(B3,2,1)="1",MID(C3,2,1)="1"),1,0)&IF(OR(MID(B3,3,1)="1",MID(C3,3,1)="1"),1,0)&IF(OR(MID(B3,4,1)="1",MID(C3,4,1)="1"),1,0)

    =IF(OR(AND(MID(B4,1,1)="1",MID(C4,1,1)="0"),AND(MID(B4,1,1)="0",MID(C4,1,1)="1")),1,0)&IF(OR(AND(MID(B4,2,1)="1",MID(C4,2,1)="0"),AND(MID(B4,2,1)="0",MID(C4,2,1)="1")),1,0)&IF(OR(AND(MID(B4,3,1)="1",MID(C4,3,1)="0"),AND(MID(B4,3,1)="0",MID(C4,3,1)="1")),1,0)&IF(OR(AND(MID(B4,4,1)="1",MID(C4,4,1)="0"),AND(MID(B4,4,1)="0",MID(C4,4,1)="1")),1,0)

  10. Michael Azer says:

    Sorry my last post was totally messed up

    AND
    =IF(AND(MID(B2,1,1)="1",MID(C2,1,1)="1"),1,0)&IF(AND(MID(B2,2,1)="1",MID(C2,2,1)="1"),1,0)&IF(AND(MID(B2,3,1)="1",MID(C2,3,1)="1"),1,0)&IF(AND(MID(B2,4,1)="1",MID(C2,4,1)="1"),1,0)
    OR
    =IF(OR(MID(B3,1,1)="1",MID(C3,1,1)="1"),1,0)&IF(OR(MID(B3,2,1)="1",MID(C3,2,1)="1"),1,0)&IF(OR(MID(B3,3,1)="1",MID(C3,3,1)="1"),1,0)&IF(OR(MID(B3,4,1)="1",MID(C3,4,1)="1"),1,0)
    XOR
    =IF(OR(AND(MID(B4,1,1)="1",MID(C4,1,1)="0"),AND(MID(B4,1,1)="0",MID(C4,1,1)="1")),1,0)&IF(OR(AND(MID(B4,2,1)="1",MID(C4,2,1)="0"),AND(MID(B4,2,1)="0",MID(C4,2,1)="1")),1,0)&IF(OR(AND(MID(B4,3,1)="1",MID(C4,3,1)="0"),AND(MID(B4,3,1)="0",MID(C4,3,1)="1")),1,0)&IF(OR(AND(MID(B4,4,1)="1",MID(C4,4,1)="0"),AND(MID(B4,4,1)="0",MID(C4,4,1)="1")),1,0)

  11. Stephen says:

    @stefan,
    I just couldn't get your solutions to work.
    01010101010 + 01010101110 = 02020210120
    what am i doing wrong?

  12. Stephen says:

    @anup
    ...I got yours to work!

  13. Rich says:

    @Stephen - I get the same, but Stef@an's second solution for AND does work (at least for the test cases I used)

  14. Stef@n says:

    @ Stephen / Rich
    yes , you are right ! - only this works:

    OR
    =1*SUBSTITUTE (A1+A2;2;1)
    XOR
    =1*SUBSTITUTE (A1+A2;2;0)
    AND
    =1*SUBSTITUTE (SUBSTITUTE (A1+A2;1;0);2;1)

  15. Michael Azer says:

    @Stef@n - You're answer is really smart, I never knew about the substitute function before. Great Work!

  16. Stef@n says:

    Thx Michael 🙂
    yes - it is simply easy 😉
    if you add 1 and 1 - excel calculate 2
    and then you have to substitute the 2 - new = 0 respectively 1

  17. Rob says:

    Here is a good resource for people wanting to learn binary and hexadecimal.
    http://justwebware.com/bitwise/bitwise.html

  18. Kyle McGhee says:

    Three that weren't asked for:
    NOT
    =SUBSTITUTE(SUBSTITUTE(SUBSTITUTE(A1+A2,0,3),1,0),3,1)

    EQV
    =SUBSTITUTE(SUBSTITUTE(SUBSTITUTE(SUBSTITUTE(A1+A2,0,3),2,3),1,0),3,1)

    IMP
    =SUBSTITUTE(SUBSTITUTE(A1+SUBSTITUTE(SUBSTITUTE(SUBSTITUTE(A2,0,3),1,0),3,1),0,1),2,0)

    (was using Daniel Ferry's bitwise file to verify against)

  19. Q says:

    @ Kyle

    Not only takes one parameter and inverts 0 -1 and 1-0

    Took out the +A2
    =SUBSTITUTE(SUBSTITUTE(SUBSTITUTE(A1,0,3),1,0),3,1)

  20. Great solutions!

    I'll add two:

    NAND =1*SUBSTITUTE (A1+A2,2,0)

    NOR=1*SUBSTITUTE(SUBSTITUTE (SUBSTITUTE(A1+A2,0,2),1,0),2,1)

  21. John Fuller says:

    This will work for binary numbers of any size (although the text format mask will have to have as many zeroes as there are digits in the longest addend)

    Assume binary #s are in C35 & C36, then add and format as text in C37:
    =TEXT(C36+C35,"000000000000")
    -sum- = 101112211112

    AND - SUBSTITUTE 0s for 1s in -sum-, then sub 1s for 2s
    =SUBSTITUTE(SUBSTITUTE(C37,"1","0"),"2","1")

    OR - sub 1s for 2s in -sum-
    =SUBSTITUTE(C37,"2","1")

    XOR - sub 0s for 2s in -sum-
    =SUBSTITUTE(C37,"2","0")

  22. Shane says:

    Just wandered by:

    AND:

    =SUBSTITUTE(A1+A2,1,0)/2

  23. Ronald Vonk says:

    Hi Chandoo,

    I am not (yet) really into bitwise calculation, but I am looking for a way to speed up my vba calculation with very big numbers. Would is ben convenient to use bitwise notation for this?

    Best regards,

    Ronald (the Netherlands)
    p.s. love your country!

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