Enum Vs #define

To a large degree, it's a matter of taste.

I prefer enums when I have a number of related integer constants. Enums are clearly preferable when you don't care what the values are. But even when you do need to specify the values for all the constants, I like the mental grouping of an enum. Code documents itself better when you have the type, e.g.

Error MyFunc();

clearly returns one of a particular set of error codes, whereas

int MyFunc()

might return one of the #define'd list for Unix errno, or maybe something else, or maybe those plus some idiosyncratic values -- who knows? If you have more than one set of return codes, which set does this function use?

The more specific enum type name helps the tags facility in your editor, greps, debugging, and so on.

A strict lint may give you some warnings about using enums as integers, for example if you add or or them, or pass an enum to an int.

A const object is different from either an enum or a #define, particularly in C. In ANSI C, a const int takes up space just as a regular int; most compilers will also generate pointer references to this address rather than inlining the value. As a result, I rarely use const int's in C. (C++ has slightly different semantics, and so the choices are different there.)

Every compiler I've ever used has the option to store enums in the smallest space possible. Usually it's even the default option. To force wider enums when using such an option, I usually throw in an extra unsigned value:

typedef enum
    {
    MyEnumA,
    MyEnumB,

    MyEnumForce16 = 7fff
    } MyEnum;

To a large degree, it's a matter of taste.

I prefer enums when I have a number of related integer constants. Enums are clearly preferable when you don't care what the values are. But even when you do need to specify the values for all the constants, I like the mental grouping of an enum. Code documents itself better when you have the type, e.g.

Error MyFunc();

clearly returns one of a particular set of error codes, whereas

int MyFunc()

might return one of the #define'd list for Unix errno, or maybe something else, or maybe those plus some idiosyncratic values -- who knows? If you have more than one set of return codes, which set does this function use?

The more specific enum type name helps the tags facility in your editor, greps, debugging, and so on.

A strict lint may give you some warnings about using enums as integers, for example if you add or or them, or pass an enum to an int.

A const object is different from either an enum or a #define, particularly in C. In ANSI C, a const int takes up space just as a regular int; most compilers will also generate pointer references to this address rather than inlining the value. As a result, I rarely use const int's in C. (C++ has slightly different semantics, and so the choices are different there.)

Every compiler I've ever used has the option to store enums in the smallest space possible. Usually it's even the default option. To force wider enums when using such an option, I usually throw in an extra unsigned value:

typedef enum
    {
    MyEnumA,
    MyEnumB,

    MyEnumForce16 = 7fff
    } MyEnum;