C compilers and non-ASCII systems

On 1 Feb 2012 at 1:31, Mouse wrote: So, on a system with, say, sign-magnitude arithmetic, masking the sign off after every operation to force a positive result is perfectly legitimate way to implement the unsigned type. Must C language elements be represented by binary numbers? I've read and heard that it's impossible, but is it really? Suppose that a machine operated natively in decimal mode. Logical operation (shift, & | ~ ^) could be implemented as either arithmetic (left-shift by doubling; right by halving) or by table lookup or even conversion to a simply binary form on which the operation would be performed, then converted back to decimal. Would that machine conform to the C standard? Can a ones-complement machine conform to the C standard? In other words, could one elminate -0 from signed arithmetic results and end up with a conforming machine? --Chuck P.S. Forgive me, but since I'm talking wtih someone who knows, I can get these nagging questions authoritatively answered.