Thread: Bit operator in c programming

In the c programming, operations can be performed on a bit level using bit wise operator

Bits that are 0 become 1, and those that are 1 become 0. For example:

bit a ~a
0 1
1 0

I have used bit wise operator in program output should be 0 but it show output -2. why does it show -2 ?

Code:

#include<stdio.h>
 
int main()
{
            
   int a = 1;
 
   printf(" addition   %d \n", ~a);
 
   return 0;
}

Result -2

Originally Posted by GReaper

It shows -2 because the computer uses two's complement to represent negative numbers, and the ~ operator inverts all the bits, not just the first one.

Long story short, the negative of a binary number "n" can be represented as "~n + 1"

Thank you for your reply. I was trying to write c program for following condition with bitwise operator

bit a ~a
0 1
1 0

How to test above condition ?

I'm not really sure I understand what you're getting at, but if you want to make 1 into binary 10, the simplest thing to do is add.

You could also xor 3, since 1 xor 3 = 2.

Originally Posted by abhi143

Thank you for your reply. I was trying to write c program for following condition with bitwise operator

bit a ~a
0 1
1 0

How to test above condition ?

Why do not you use unsigned rather than signed values ?

AFAIK you rarely use bit-twiddling with signed values.