Hi mates!

How do you create enums for state charts in ObjC?
Usually, in C++ I do something like:

enum GAME_STATE {
STARTING,
PLAYING,
...
ENDING
};
GAME_STATE m_game_state;

But it seems "enum" does not exist in ObjC.
How do you usually implement state charts or finite state machines in ObjC? I mean, How do you exactly represent states?

Thanks a lot.

enum's exist in C, and as Objective-C is a strict superset of C they exist in that also; the following compiles happily in Objective-C:

sealfin Wrote:enum's exist in C, and as Objective-C is a strict superset of C they exist in that also; the following compiles happily in Objective-C:

Code:

typedef enum
{
STARTING,
PLAYING,
ENDING
}
GAME_STATE;

[i][snip][/i]

GAME_STATE m_game_state;

Thanks for reply.
Just one question, in my C++ programs I don't use typedef before enum, why do I have to use typedef if C has enums?

Thanks.

Because C++ is not a strict superset of C: link.

sealfin Wrote:Because C++ is not a strict superset of C: link.

Thanks!

I guess you are talking about:
"A struct, union, or enum declaration in C++ is a first class type, while in C it is not."
isn't it?

This is interesting stuff. I had a similar problem, except it would just give me warnings saying that the statement did not declare anything. This happened when trying to declare the enum in the scope of a class interface. Simply moving it to global scope fixed the problem. Also, when declaring instances of the enum, I always had to put the "enum" before the declaration. For example:



Any thoughts?

Instance variables go between those braces, not any old declaration you like.

In C, "struct S { ... }" declares a type called "struct S", and "enum E { ... }" declares a type called "enum E". In C++, "struct S { ... }" declares a type with two names, "struct S" and "S", and "enum E { ... }" declares a type with two names, "enum E" and "E". To get the simpler name like C++ in C you need a typedef, for example "struct S { ... }; typedef struct S S;", or you can shorten that to "typedef struct S { ... } S;".

Or if you don't care about having a custom type you can just do (in C):

enum {
STARTING,
PLAYING,
ENDING
};