What is “2's Complement”?

Question

I\'m in a computer systems course and have been struggling, in part, with Two\'s Complement. I want to understand it but everything I\'ve read hasn\'t brought the p

Answer 1

In simple term 2's Complement is a way to store negative number in Computer Memory. Whereas Positive Numbers are stored as Normal Binary Number.

Let's consider this example,

Computer uses Binary Number System to represent any number.

x = 5;

This is represented as 0101.

x = -5;

When the computer encouters - sign, it computes it's 2's complement and stores it. i.e 5 = 0101 and it's 2's complement is 1011.

Important rules computer uses to process numbers are,

1. If the first bit is 1 then it must be negative number.
2. If all the bits except first bit are 0 then it is a positive number because there is no -0 in number system.(1000 is not -0 instead it is positive 8)
3. If all the bits are 0 then it is 0.
4. Else it is a positive number.