How to use logical XOR operator in macro? NOT how to defined XOR operator by macro [duplicate]

Question

Is there any tricky way to use logical xor operator ^^ in macro in C, C++, Objective-C?

I have tried applying ^^ directly in Objective-C, it does not work.

Edited: let me clarify my answer.

What I want is to use xor operator in macro. It does not mean "how to define the xor operator by a macro.

I.e, I want something like

#if defined(x) ^^ TARGET_OS_IOS ^^ __cplusplus

By summoning a minimum of C programming knowledge, you can write such an operator yourself, in less than 10 seconds. #define XOR(a,b) ( ((a)!=0) ^ ((b)!=0) ). — Lundin
– Lundin, Commented Feb 23, 2017 at 9:38
@Lundin: my question is to use logical xor operan IN MACRO. I also want to use it though multiple file. With your solution, I have to include the header file including that macro, of course, it is not efficient — Sang
– Sang, Commented Feb 23, 2017 at 11:30
@tranvansang Macros are evaluated by the pre-processor, making them very efficient. But you don't have to implement it as a macro, you can simply use ((a)!=0) ^ ((b)!=0) anywhere in the code. It yields the very same machine code. — Lundin
– Lundin, Commented Feb 23, 2017 at 11:50

Sang · Accepted Answer · 2021-07-21 01:14:56Z

2

For seconds after posting the question, I figured out the answer my self.

!(A) != !(B) will be equivalent to xor operator

A better solution in case the number of operands is different than 2

!(A) ^ !(B) ^ !(C) ^ ...

answered Feb 23, 2017 at 9:07

Sang

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2 Comments

You can remove the ! infront of the variables A != B should also do the job

@Aeonos The ! are necessary if A and B are integer types other than bool. Consider A=1; B=2