C++ - Bit-wise not of uchar produces int

Question

I am surprised by C++\'s behavior when applying bit-wise not to an unsigned char.

Take the binary value 01010101b, which is 0x55, or

Answer 1

The answer about integral promotion is correct.

You can get the desired results by casting and NOTting in the right order:

assert(static_cast(0xAAu) == static_cast(~0x55u));