Bit field vs Bitset

Question

I want to store bits in an array (like structure). So I can follow either of the following two approaches

Approach number 1 (AN 1)

struct BIT
{
   int da         


        

Answer 1

A good choice depends on how you're going to use the bits.

std::bitset is of fixed size. Visual C++ 10.0 is non-conforming wrt. to constructors; in general you have to provide a workaround. This was, ironically, due to what Microsoft thought was a bug-fix -- they introduced a constructor taking int argument, as I recall.

std::vector is optimized in much the same way as std::bitset. Cost: indexing doesn't directly provide a reference (there are no references to individual bits in C++), but instead returns a proxy object -- which isn't something you notice until you try to use it as a reference. Advantage: minimal storage, and the vector can be resized as required.

Simply using e.g. unsigned is also an option, if you're going to deal with a small number of bits (in practice, 32 or less, although the formal guarantee is just 16 bits).

Finally, ALL UPPERCASE identifiers are by convention (except Microsoft) reserved for macros, in order to reduce the probability of name collisions. It's therefore a good idea to not use ALL UPPERCASE identifiers for anything else than macros. And to always use ALL UPPERCASE identifiers for macros (this also makes it easier to recognize them).

Cheers & hth.,