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[Geek19]

I am trying to use the folowing # define statement

//-------------------------------------

#idndef  _THISFILE_

#define  _THISFILE_

:

//some definitions here

:

#endif

//-----------------------------------

 and use this  header file in various  .C files, and to my surprise I get the "Multiple definition" error and I am wondering if there is any option in the IDE i have to setup? Could you please explain this and let me know about a possible workaround as well.

I also have problem with defining a structure as  "extern" while I have defined it as a  "typdef" of a structure in another file? the compiler complains about illigal definition of the extern!? is there any other way to define this with no error?

Thanks;

[stanish]

Hello Geek19

 
The define statement you mentioned protects a single compilation unit (single .c file) from including the multiple definitions of the same header file.
I assume you are able to compile but there is a linker error right?
Can you double check if the header files included does not contain any object definition?

e.g. "thisfile.h":
--------------------
#idndef  _THISFILE_
#define  _THISFILE_
...
 int my_object  = 10;
...
#endif

In such particular case "my_object" is allocated in each .c file that includes thisfile.h.

Regarding the extern struct see the example below that should work:

e.g. "thisfile.h":
--------------------
#idndef  _THISFILE_
#define  _THISFILE_
...
typedef struct
{
  int a;
  int b;
}tMyStruct;

extern tMyStruct my_struct;  

// header file includes just extern declaration ( type tMyStruct must be available in .h file or included from separate .h file)
...

#endif


thisfile.c
-----------
#include "thisfile.h"
tMyStruct my_struct;   // here the memory is allocated to the struct variable
...

If this does not help please post some code snippets...

Stanish