Signed integers (cont)
Ones complement: Easy to form -X from X ... NEG all bits
A problem (using 8-bit ints) ...
- what do these numbers represent?
00000000, 11111111
Two zeroes ... one positive, one negative
At least x + -x is equal to one of the zeroes with simple addition
00000011 3 00101010 42 01111111
+ 11111100 -3 + 11010101 -42 + 10000000
-------- -------- --------
11111111 -0 11111111 -0 11111111 -0
|
|
![[prev]](icon/prev.gif){kind=icon}
![[next]](icon/next.gif){kind=icon}