Why must bitfields sum to a multiple of a byte?

[Andrej Mitrovic]

On 7/31/12, Era Scarecrow <rtcvb32 at yahoo.com> wrote:
>   And likely one I'll be working on fairly soon. I've been
> concentrating on the BitArray, but I'll get more of the bitfields
> very very soon.
>

Cool. What about the max limit of 64bits per bitfield instantiation? I
don't suppose this is common in C++ but I wouldn't know..