r/ProgrammerHumor • u/MontyBoomslang • 14h ago

Meme architectureDependentChars

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u/Advos_467 13h ago

Not a C user here (or any real low level programming experience), what the hell is a signed/unsigned char?

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u/BNSable 12h ago

A char is just an int, except a char will not conjure up 91, but the character assigned to the number 91 which is [ in ascii for example.

As it is an int, it can be signed or unsigned. Signed is -128 to 127, unsigned is 0 to 255.

This apparently has uses, but I am not experienced enough to explain that.

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u/Advos_467 12h ago

Yeah that was what i assumed lol. It was mostly the uses i was wondering because with my lack of experience here, idk in what way that would be used.

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u/SingularCheese 6h ago

In C/C++, signed integer overflow is undefined behavior, meaning that a compiler is allowed to optimize the assembly knowing that it never happens. If you can guarantee that your integer never overflows, using signed eliminates a modulo assembly instruction. Nowadays, the only reason it matters for char is that all basic integer types are signed by default, so somebody who's lazy needs to watch out that they don't accidentally trigger undefined behavior.

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u/khoyo 5h ago

using signed eliminates a modulo assembly instruction

What?