C bit boolean logic

Question

I have the following C statement:

int res = x & (x ^ y);

Is there a way to do the same thing, but using x and y only one time each?

For example:

x | (~x & y) == x | y

Oliver Charlesworth · Accepted Answer · 2012-05-14 13:53:17Z

7

Yes, by expanding the xor (a ^ b == (a & ~b) | (~a & b)), and then simplifying the result, one gets:

res = x & ~y;

answered May 14, 2012 at 13:38

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Comments

MByD · Accepted Answer · 2012-05-14 13:39:12Z

4

x & (x ^ y) sets the bits that are set on x and set on x^y e.g. not set on y.

So you can do:

int res = x & ~y;

answered May 14, 2012 at 13:39

MByD

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