Question

i have question on this topic i think that answer is incorrect look

Swap bits in a number in C

1110 1011 it is equal 235 but i get 3051 why?

Answer 1

The value 3051 in decimal is 101111101011 in binary. If you split it up into four bit segmens like this: 1011 1110 1011, you see that the lowest four bits are repeated above the eight bits that you want. The reason for that is that you haven’t masked the value that should be the top four bits.

So instead of something like this:

(c >> 4) | ((c & 0x0f) << 4)

or something like this:

((c >> 4) | (c << 4)) & 0xff

you simply have this:

(c >> 4) | (c << 4)