Bits to Byte in C++

Question

I'm trying to:

1. convert a group of 8 integers, all of value 0 or 1, into a byte
2. reverse the bit order of that byte
3. print the value of that byte (in what format?) ( i can guess until i have it right here )

Also, I'm not allowed to use the STL for this problem.

Answer 1

So, you want to reverse the bits in a byte. That is, the bits should move so:

from: 7 6 5 4 3 2 1 0
to:   0 1 2 3 4 5 6 7

This code will do it, inelegantly - you can find much better algorithms if you search. Can you see how it works though?

uint8_t reverse_bits(uint8_t byte)
{
    return ((byte & 0x01) << 7)
          |((byte & 0x02) << 5)
          |((byte & 0x04) << 3)
          |((byte & 0x08) << 1)
          |((byte & 0x10) >> 1)
          |((byte & 0x20) >> 3)
          |((byte & 0x40) >> 5)
          |((byte & 0x80) >> 7);
}

Answer 2

A simple method is to mask rest of bits, as you can see in way to read individual bits.