Why 1s complement is -2

[gourabbanik05]

int main()
{
       int a=1,b;
       b=~1;
       printf(""%d",b);
       return 0;
}

pls explain by showing bitwise operation it will be helpful to understand...

thanks in advance.......

[laserlight]

Please do your own homework. You can easily find a rather direct answer to this by searching the Web.

[GReaper]

Think it as binary:

00000000000000000000000000000001 // 1

What does NOT do:

11111111111111111111111111111110 // -2

Since you are declaring it as signed the compiler treats it are a little negative instead of a large positive.

[Adak]

Think of the sign bit, only:

The sign bit can be a one or a zero. If the sign bit isn't a one, then it must be a zero, and vice-versa.

What else could a complement of a positive number be, since you've changed the sign bit?

Now apply that to all the bits in the binary for 1.

[gourabbanik05]

many many thanks to Sipher & Adak for their valuable time and lucid explanation...........