How ~10 is -11?

#1

~ is 1’s complement. So ~1010 is 0101 which is 5 in decimal not -11.

#2

‘~’ is the bitwise NOT operation.
Bitwise NOT changes each bit to its opposite: 0 becomes 1, and 1 becomes 0.
And the sign bit also changes.
So ~10 is -11.

#3

The result of ~ operator on a small number can be a big number if the result is stored in an unsigned variable. And the result may be a negative number if the result is stored in a signed variable (assuming that the negative numbers are stored in 2’s complement form where the leftmost bit is the sign bit).
Check this code -

#include

using namespace std;

int main()
{
unsigned int x = 1;
printf(“Signed Result %d \n”, ~x);
printf(“Unsigned Result %ud \n”, ~x);
return 0;
}

Output:
Signed Result -2
Unsigned Result 4294967294d

#4

I got why sign changes but how is 10 becoming 11 ?
Because 10 is 1010
so when bits are changing it should become
1010, which is not 11.
Please correct if I am wrong.

#5

10 in binary is represented as 01010. Leftmost bit is the sign bit. 0 for positive and 1 for negative.
So 10 = 0*(2^0) + 1*(2^1) + 0*(2^2) + 1*(2^3) - 0*(2^4)
Now reversing the bits - 10101
1*(2^0) + 0*(2^1) + 1*(2^2) + 0*(2^3) - 1*(2^4) = 1 + 0 + 4 + 0 - 16 = 5 - 16 = -11.

#6

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