I have a byte called "x". I want byte "y" to be the complement of
"x" (i.e. all the bits flipped).

Initially I wrote:

char unsigned x, y;

...

x = 72;

y = ~x;

But then I thought that the following might happen on your average
system (CHAR_BIT == 8, sizeof(int) == 4):

1) x is promoted to signed int.
2) The complement is take of this signed int.
3) This signed int is then converted to an unsigned char

Am I right in thinking that this is what will happen? If so, would I
be wise to do the following instead:

y = ~(unsigned)x;

--
Tomás Ó hÉilidhe