What is the most efficient way to represent small values in a struct?

Question

Often I find myself having to represent a structure that consists of very small values. For example, Foo has 4 values, a, b, c, d that, range from

Answer 1

Code it with ints

treat the fields as ints.

blah.x in all your code, except the declarion will be all you will be doing. Integral promotion will take care of most cases.

When you are all done, have 3 equivalant include files: an include file using ints, one using char and one using bitfields.

And then profile. Don't worry about it at this stage, because its premature optimization, and nothing but your chosen include file will change.