Implementing BitVector - 1

size_t BitVector::ByteNumber (size_t index) const
{
  // return index / 8
  // shift right 3 is equivalent to, and faster than, dividing by 8
  index = index >> 3;
  return index;
}

unsigned char BitVector::Mask (size_t index) const
{
  // return mask for index % 8
  // the low order 3 bits is the remainder when dividing by 8
  size_t shiftamount = index & (size_t)0x07;  // low order 3 bits
  return 0x01 << shiftamount;
}