Determining the sign of an int using shifts?

Question

Here's the question

• sign - return 1 if positive, 0 if zero, and -1 if negative
• Legal ops: ! ~ & ^ | + << >>
• Max ops: 10
• Rating: 2

I thought of shifting to the right by 31 to grab the sign bit but can't 0 be positive AND negative technically?

Answer 1

You may try like this for 32 bit int:-

(x >> 31) | (((~x + 1) >> 31) & 1)