shortest way to check if a positive integer is a power of two [duplicate]

Question

This question is from job interview...
Use this template to write a C++ function that checks if a positive integer is a power of two.

bool p(int n) { return ********; }

You have to replace the 8 '*' symbols with other symbols in order to make the function work correctly.
My best approach was this:

bool p(int n) { return !(n&=n-1); }

Unfortunately it was wrong, because there are 9 symbols here...
Any ideas?

LogicStuff · Accepted Answer · 2015-10-30 22:15:43Z

0

Why assign to n? Just remove = and you have one character less. It will create a temporary instead, the logic won't change.

answered Oct 30, 2015 at 21:51

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3 Comments

well, I thought '&' had a higher priority than '-' Thank you!

Then replace that eight stars with call to the function from the duplicate :)