#define or enum? [duplicate]

Answer 1

Since the states are related elements I think is better to have an enum defining them.

Answer 2

Technically it doesn't matter. The compiler will most likely even create identical machine code for either case, but an enumeration has three advantages:

1. Using the right compiler+debugger combination, the debugger will print enumeration variables by their enumeration name and not by their number. So "StateBlahBlup" reads much nicer than "41", doesn't it?

2. You don't have explicitly give every state a number, the compiler does the numbering for you if you let it. Let's assume you have already 20 states and you want to add a new state in the middle, in case of defines, you have to do all renumbering on your own. In case of enumeration, you can just add the state and the compiler will renumber all states below this new state for you.

3. You can tell the compiler to warn you if a switch statement does not handle all the possible enum values, e.g. because you forgot to handle some values or because the enum was extended but you forgot to also update the switch statements handling enum values (it will not warn if there's a default case though, as all values not handled explicitly end up in the default case).

Answer 3

enum is great when you have exclusive options, but you can't use them to define bitfield flags, like this:

#define SQ_DEFAULT 0x0
#define SQ_WITH_RED 0x1
#define SQ_WITH_BLUE 0x2

void paint_square(int flags);

Then you can paint red-blue square with:

paint_square(SQ_WITH_RED | SQ_WITH_BLUE);

...which you can't with enum.