Is the result of a boolean operation 1 or 0 in C?

Question

Is the result of a boolean operation guaranteed to be 1 or 0?

I'm programming a microcontroller and need to set a pin to 1 or 0, and was wondering if I can shorten the code from this:

isRunning = isStarted && !isSleeping;
_PBH0 = isRunning ? 1 : 0;

to this:

isRunning = isStarted && !isSleeping;
_PBH0 = isRunning;

@devnull What do you mean? Aren't all answers about the standard "by definition"? (or did I miss a pun?) — Andreas, Sep 19 '13 at 08:47

score 7 · Accepted Answer · edited Jun 20 '20 at 09:12

7

Yes, the result of && operator (or any of the logical operators) is an int that has a value of either 1 or 0.

C11 §6.5.13 Logical AND operator

The && operator shall yield 1 if both of its operands compare unequal to 0; otherwise, it yields 0. The result has type int.

edited Jun 20 '20 at 09:12

Community

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answered Sep 19 '13 at 08:11

Yu Hao

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Thanks. Do `||` and `!` also return either 1 or 0? – Andreas Sep 19 '13 at 08:28
@Andreas Yes, that's what I mean by *any of the logical operators*. – Yu Hao Sep 19 '13 at 08:31

score 2 · Answer 2 · answered Sep 19 '13 at 08:16

2

Infact, you can reduce to_PHB0 = (isStarted && !isSleeping);

answered Sep 19 '13 at 08:16

nj-ath

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Is the result of a boolean operation 1 or 0 in C?

2 Answers2

C11 §6.5.13 Logical AND operator