0360. What is one’s compliment? What is two’s compliment? Which do we use and why??

One’s compliment is straight-forward complimenting (see previous question). However, problems can occur. We can end-up with a -0 (negative zero). To counteract the problem, iff the result of adding a negative number is non-negative, we must add ‘1’ to the result.

In two’s compliment, we perform a one’s compliment and then add one to the result.

Most machines use two’s compliment because in one’s compliment we can add numbers together and end-up with a -0 (negative zero), whereas in two’s compliment, we can not.