Check if a number x is positive (x>0) by ONLY using bitwise operators in C

Question

isPositive - return true if x > 0, otherwise false

Example: isPositive(-1)

Legal ops:

Answer 1

Let's play with the sign bit: sign(~n) : 1 if n >= 0

To get rid of the case when n is 0: sign(~n + 1) : 1 if n > 0 or n = MIN_INT

So, we want the case when both functions return 1:

return ((~n & (~n + 1)) >> 31) & 1;