Source file can't see a define from other header

Question

I have a custom header file ("strings.h"):

#ifdef __cplusplus
#if __cplusplus
extern "C"{
#endif
#endif /* __cplusplus */
#include "sdkGlobal.h"

#ifdef __cplusplus
#if __cplusplus
}
#endif
#endif /* __cplusplus */

#if !defined administration_H_
#define administration_H_

#define POS_STR_TITLE_OPERATIONS "somestr"

#endif

In one of the source files I have:

#include "../inc/strings.h"

In the code when I use:

    sdkShow (LINE3, 0, POS_STR_TITLE_OPERATIONS );

I get error:

src/main.c: In function 'postMainMenu':
src/main.c:190: error: 'POS_STR_TITLE_OPERATIONS ' undeclared (first use in this function)
src/main.c:190: error: (Each undeclared identifier is reported only once
src/main.c:190: error: for each function it appears in.)
make[1]: *** [src/main.o] Error 1
make: *** [all] Error 2

Any ideas why?

Answer 1

the guard should always reflect the name of the header-file to guard, so it should be "strings_H_" and "sdkGlobal_H_"

it is intended for greater products where header-files have dependencies of their own. for example "a.h" needs "length.h" and "b.h" needs "length.h" also, you guard "length.h" to be evaluated once.

Answer 2

It seems administration_H_ is already defined.So rather than

#if !defined administration_H_
#define administration_H_

#define POS_STR_TITLE_OPERATIONS "somestr"

#endif

you intended

#if !defined administration_H_
#define administration_H_
#endif

#if !defined POS_STR_TITLE_OPERATIONS
#define POS_STR_TITLE_OPERATIONS "somestr"
#endif