Difference between Enum and Define Statements

enum defines a syntactical element.

#define is a pre-preprocessor directive, executed before the compiler sees the code, and therefore is not a language element of C itself.

Generally enums are preferred as they are type-safe and more easily discoverable. Defines are harder to locate and can have complex behavior, for example one piece of code can redefine a #define made by another. This can be hard to track down.

#define statements are handled by the pre-processor before the compiler gets to see the code so it's basically a text substitution (it's actually a little more intelligent with the use of parameters and such).

Enumerations are part of the C language itself and have the following advantages.

1/ They may have type and the compiler can type-check them.

2/ Since they are available to the compiler, symbol information on them can be passed through to the debugger, making debugging easier.

Define is a preprocessor command, it's just like doing "replace all" in your editor, it can replace a string with another and then compile the result.

Enum is a special case of type, for example, if you write:

enum ERROR_TYPES{   REGULAR_ERR =1,   OK =0}

there exists a new type called ERROR_TYPES.It is true that REGULAR_ERR yields to 1 but casting from this type to int should produce a casting warning (if you configure your compiler to high verbosity).

Summary:they are both alike, but when using enum you profit the type checking and by using defines you simply replace code strings.