Why the absolute value of the max negative integer -2147483648 is still -2147483648?

Question

The result of abs(-2147483648) is -2147483648, isn\'t it? it seems unacceptable.

printf(\"abs(-2147483648): %d\\n\", abs(-2147483648));

out

Answer 1

Negative numbers are usually represented whit binary complement.

To convert positive to negative it is used logic

x -> not(x)+1

For 8 bits arithmetic

01111111b is 127 and -127 becomes
10000000b + 1 = 10000001b

and to opposite direction -127 10000001b becomes
01111110b + 1 = 01111111b

What about -128?

-128 is 10000000b and there is no positive counterpart of it, because there is no 128 in 8 bits signed arithmetic.

10000000 -> 01111111 + 1 = 10000000 and -128 again

Same applies to original question