Re: [Mingw-users] Multiple definition error

[Michael G. <mg...@te...>]

>    I'm having a problem with a FILE pointer declared inside a header.
> When I try to link it, i got an "multiple definition" error. Here is a
> small test case:

The probelm is you indeed _define_ it twice:
wherever you include utils.h the filepointer is defined. What you
actually want to do is define it once and _declare_ it everywhere
else.

There are a couple of mechanisms to achieve that:
1) Copy the line in utils.h into main.c and change utils.h as follows
   extern FILE *system_log_file;
2) Change utils.h as follows
   #if defined(IN_MAIN)
   FILE *system_log_file =3D NULL;
   #else
   extern FILE *system_log_file;
   #endif
   and insert
   #define IN_MAIN
   in main.c before including utils.h

There are variations to this but you get the idea.

HTH, best,
Michael
=2D-=20
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 Michael Gerdau       email: mg...@te...
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