Change sign using bitwise operators

Question

How to change the sign of int using bitwise operators? Obviously we can use x*=-1 or x/=-1. Is there any fastest way of doing this?

I did a sm

Answer 1

Solution using high level language

Questions like these are popular in interviews and competitive programming world .

I landed here researching more solution for negation of a number without using - or + operator .

For this :

1. complement a number using ~ operator

2. Then add 1 to the number obtained in step 1 using Half adder logic :

   int addNumbers(int x, int y) { 
               if(y==0) return x; // carry is 0 return 
               addNumbers(x^y,(x&y)<<1); }
   

Here x^y performs addition of bits and x&y handles carry operation