Question

Given that signed and unsigned ints use the same registers, etc., and just interpret bit patterns differently, and C chars are basically just 8-bit ints, what’s the difference between signed and unsigned chars in C? I understand that the signedness of char is implementation defined, and I simply can’t understand how it could ever make a difference, at least when char is used to hold strings instead of to do math.

Answer 1

It won’t make a difference for strings. But in C you can use a char to do math, when it will make a difference.

In fact, when working in constrained memory environments, like embedded 8 bit applications a char will often be used to do math, and then it makes a big difference. This is because there is no byte type by default in C.