I use
enum SomeEnum
{
FIRST = 1,
One = 1,
Two = 2,
Three = 3,
LAST = 3
}
Jason Iverson
2010-10-21 01:02:22
+2
A:
Would it be `One = FIRST,` instead? If somebody later wants to add another enumerated value e.g. `Four = 4`, it must be remembered to change the `LAST = ` line to `4`. Though it sounds trivial, in reality, it turns out to be hard, i.e. easy to miss :)
ArunSaha
2010-10-21 01:10:26
I like that idea. I'll try that with my next enum and see how it feels.
Jason Iverson
2010-10-21 01:12:26
Just don't put the numbers in except FIRST = 0 and let the others go from there, that way if there are four items then LAST equals five, it is one more than the largest position which is easy to deal with and is nicer (IMO) in for loops if you prefer i < LAST rather than i <= LAST.
Robert Massaioli
2010-10-21 01:13:37
+4
A:
it's not totally obvious what you are asking for, but supposing you have an enum like:
enum Fruits
{
Apples,
Bananas,
Pineapples,
Oranges,
};
You could modify it like so:
enum Fruits
{
Apples = 0,
Bananas,
Pineapples,
Oranges,
NUM_FRUITS; // must be last, and no other fruits can be given values.
};
The Apples = 0, isn't strictly neccesary, it could still be just Apples, because that will be the result by default, but it's a good idea because it makes it clear that you actually care what value it takes.
And thus, Fruits::NUM_FRUITS would equal 4. If you added two more fruits, being careful to place them above the NUM_FRUITS, and making sure the first fruit mentioned is set to zero, either implicitly or explicitly, then NUM_FRUITS will instead be 6.
TokenMacGuy
2010-10-21 01:13:33
+1 -- I think this is more consistent than Jason Iverson's answer -- unless one want to use his or her own `enum` values.
Archie
2010-10-21 01:28:27
A:
No, there's no general automatic solution after the enum's been created. If you're prepared to force people to declare their enums via a macro, and your compiler supports variadic macros, you can have a macro that creates the enum and captures the number of elements (stringify, scan for commas ignoring whatevers inside pairs of < >, ( ), [ ] etc..
Tony
2010-10-21 01:39:34