> Are chars *supposed* to be signed or unsigned by default?

No.

At least if I may wear my comp.lang.c hat for a moment, there are three
"char" variants: char, signed char, and unsigned char.  Plain char is
always equivalent to one of the other two, but which one is
implementation-dependent.  Possibly implementation-specified; I don't
know.  But either way is valid C.

POSIX and other standards may have other restrictions on the matter; I
don't know.  I doubt they do, since simulating the "other" type carries
a significant performance penalty on some machines.

					der Mouse

			    mouse@collatz.mcrcim.mcgill.edu