Why do unsigned int x = -1 and int y = ~0 have the same binary representation?

Question

In the following code segment what will be:

• the result of function
• value of x
• value of y

    {
         unsigned int x=-1;         


        

Answer 1

Its pretty easy. The twos complement representation of -1 is 0xFFFFFFFF. Hence that is what x contains.

The complement operator (~) flips all the bits. So the complement of 0 is a 32-bit number with all the bits set to 1 or 0xFFFFFFFF.

Edit: As pointed out int he comments. The answer is not A. If it was then it would be saying 0x7FFFFFFF and 0xFFFFFFFF are the same. They're not. The real answer is C (Assuming MAXUNIT is a typo ;)).