What does it mean for a char to be signed?

c string character-encoding char signed
dsimcha picture dsimcha · Jan 16, 2009 · Viewed 38.1k times · Source

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

Nick Fortescue picture Nick Fortescue · Jan 16, 2009

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.

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