Why are C character literals ints instead of chars?

Question

In C++, sizeof(\'a\') == sizeof(char) == 1. This makes intuitive sense, since \'a\' is a character literal, and sizeof(char) == 1 as d

Answer 1

This is only tangential to the language spec, but in hardware the CPU usually only has one register size -- 32 bits, let's say -- and so whenever it actually works on a char (by adding, subtracting, or comparing it) there is an implicit conversion to int when it is loaded into the register. The compiler takes care of properly masking and shifting the number after each operation so that if you add, say, 2 to (unsigned char) 254, it'll wrap around to 0 instead of 256, but inside the silicon it is really an int until you save it back to memory.

It's sort of an academic point because the language could have specified an 8-bit literal type anyway, but in this case the language spec happens to reflect more closely what the CPU is really doing.

(x86 wonks may note that there is eg a native addh op that adds the short-wide registers in one step, but inside the RISC core this translates to two steps: add the numbers, then extend sign, like an add/extsh pair on the PowerPC)