Re: Forward declaration issue (error: previous declaration of 'tst' was here)

[Hani Ayoub <hani dot ayoub at live dot com>]

I see... 

Anyway... I've tried to compile the same code on g++ (instead of gcc), and I
got no error :)
Don't really know why... but works fine...


Baurzhan Ismagulov wrote:
> 
> On Tue, Dec 02, 2008 at 07:30:02AM -0800, Hani Ayoub wrote:
>> >>>> tst.h
>> >>>> =======
>> >>>> typedef struct _tst{
>> >>> ...
>> >>>> } tst;
>> >>>
>> >>>> tst2.h
>> >>>> =======
>> >>>> #include "tst.h"
>> >>>>
>> >>>> int foo(tst t);
>> >>>
>> >>>> tst.c
>> >>>> =======
>> >>>> #include <stdio.h>
>> >>>> #include "tst2.h"
>> >>>>
>> >>>> int foo(tst t){ return 1; };
> ...
>> What I'm trying to do is "forward declaration"; means to hide tst struct
>> definition from source or header files that includes tst2.h file.
> 
> Then you'll want to remove #include "tst.h" from tst2.h -- struct _tst
> is exactly what you want to hide from tst2.h and tst.c -- and make
> typedef struct _tst tst available somewhere.
> 
> I personally would put typedef struct _tst tst in tst.h and hide struct
> _tst declaration within something like #ifdef INTERNAL_TST ... #endif:
> 
> tst.h
> =====
> #ifdef INTERNAL_TST
> struct _tst {
> ...
> };
> #endif
> 
> typedef struct _tst tst;
> 
> user.h
> ======
> #include "tst.h"
> int foo(tst t);
> 
> user.c
> ======
> #include "user.h"
> int foo(tst t){ return 1; }
> 
> This would provide the same header for both API-providing and API-using
> modules.
> 
> With kind regards,
> -- 
> Baurzhan Ismagulov
> http://www.kz-easy.com/
> 
> 

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