2 C enum questions

Question

Part 1

In C, is there any difference between declaring an enum like this:

typedef enum{VAL1, VAL2,} firstEnum;

and like this:

enum secondEnum{Val1, Val2,};

Apart from the fact that when using secondEnum, you have to write:

enum secondEnum...;

Part 2

Also, am I right in thinking that the following is equivalent:

enum{Val1, Val2,} enum1;

and

enum thirdEnum{Val1, Val2,}
enum thirdEnum enum1;

Thanks

Answer 1

In part 1, there is obviously a difference - first you are declaring firstEnum as a typedef for the (anonymous) enumerated type, while in the second secondEnum is the tag for the enumerated type and there is not a typedef involved. The first is recommended for the ease of use as you have noted.

In part 2, the two are not equivalent - the first declares an anonymous enumerated type and defines enum1 to be of that type. The second declares a named enumerated type and then declares enum1 to be of that type. The significance is that you can use the named type in other parts of the code, while in the first you cannot use it anywhere else so you will probably have to use integer values as alias for the values of the enumerated type.