CODEWITHSUNDEEP
cc-preprocessor
user1433755
user1433755

Reputation: 77

and bitwise operator in C preprocessor

When I try the following code:

#if 11 & 10 == 10
#endif

the evaluation of expression is true but when I change that to the following:

#if 10 & 10 == 10
#endif

The evaluation returns false, while based on definition of & operator it should still return true (when I am trying out of preprocessor that's correct). Generally, Whatever I am trying which has 0 in the first operand returns false ignoring what the result is.

Does anyone know what the problem is?

Upvotes: 5

Views: 4505

Answers (2)

aqua
aqua

Reputation: 3375

== has higher precedence than &

if 11 & 10 == 10 evaluates to if 11 & 1 evaluates to if 1

if 10 & 10 == 10 evaluates to if 10 & 1 evaluates to if 0

Upvotes: 5

chrisaycock
chrisaycock

Reputation: 37930

Order of operation seems to be the culprit since == is evaluated before &. Parentheses worked for me:

#if (10 & 10) == 10

Upvotes: 7

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