Most elegant way to share a C array

Question

I have to turn back to (embedded) C after some lengthy time with C++, and have the following problem:

I have a source module which is included a lot of times, let\'s

Answer 1

I often put the definition in the header (this is frowned upon, I know). It keeps the definition and declaration close together, which is a Good Thing.

/* file.c */
#define FILE_C 1
#include "file.h"

.

/* file.h */
#ifndef FILE_H
#define FILE_H 1

#define BIG_SIZE 13

#if FILE_C 
char the_array[BIG_SIZE];
#else
extern char the_array[BIG_SIZE];
#endif

#endif /* FlLE_H */

.

 /* other_file.c */
#include "file.h"

There is no risk of doing it wrong: the linker will complain if you do it wrong.

BTW a similar way to basically do the same, but maybe a bit more readable, is:

/* file.h */
#ifndef FILE_H
#define FILE_H 1

#if FILE_C
#define EXTERN /**/
#else
#define EXTERN extern
#endif

#define BIG_SIZE 13

EXTERN char the_array[BIG_SIZE];

...

#undef EXTERN
#endif /* FlLE_H */