CODEWITHSUNDEEP
scheme
NewToJava
NewToJava

Reputation: 11

Scheme, checking not equal int?

How can I check if 3 natural numbers are not equal (at all), 2 of the 3 are equals or all of them are equal?

The last one makes perfect sense but I am confused because of the first two. How do I check whether 2 of 3 are equal?

I had a function (define-struct (func1 num1))

I used not (= (struct-num1) (struct-num2) (struct-num3))

But it returns true if 2 or 3 are equal.

Upvotes: 1

Views: 1101

Answers (1)

tom
tom

Reputation: 22979

The straightforward way to check if three numbers are all different (e.g. 3 6 4) is to check that each pair is different:

(and (not (= a b)) (not (= a c)) (not (= b c)))

Checking that all three are equal (e.g. 4 4 4) you can do already.

If both checks return false, then exactly two must be equal (e.g. 3 6 3).

Upvotes: 1

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