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conditional statement with ||

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Say I have
If A && B && C
...do something if A = B = C = true
end
Is it faster, however to do:
If ~(A || B || C)
..do something if A or B or C = false
end
I am wondering if the latter statement is faster because it should be able break if any of the conditions are false and not test the rest. But I am wondering if the negation forces all of the conditions to be tested first?

Accepted Answer

Fangjun Jiang
Fangjun Jiang on 28 Sep 2011
If A is false, then A && B will be short-circuited. No need to use the latter approach. Use the first one because it's easy to read.

More Answers (1)

Walter Roberson
Walter Roberson on 28 Sep 2011
The two expressions are not equivalent.
A && B && C
is true only if A and B and C are all true.
~(A||B||C)
is true only if A and B and C are all false, not if one of them is false.
The logical or equivalent of A && B && C is
~(~A || ~B || ~C)
  1 Comment
Fangjun Jiang
Fangjun Jiang on 29 Sep 2011
+1, that's another sharp catch!

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