sharing structs

[stonedzealot]

Just wondering what the procedure was to share structs between two c units, the same way you share functions (just declare the function at the beginning of the unit and the linker handles it). What is the way to handle this?

[Joel (not logged in)]

Depends on what you're trying to do. If you're trying to share the type, then just use a header file (or retype the struct definition, but a header file is easier). If you're trying to share an actual variable, use the extern keyword. The following example will demonstrate both:

Code: Select all

/* structdefinition.h */

typedef struct MYSTRUCT
{
    int some_variable;
    int some_other_variable;
} MyStruct;

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/* Unit1.c */

#include "structdefinition.h"

MyStruct mystruct;

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/* Unit2.c */

#include "structdefinition.h"

/* the following declaration references the same
    variable that is declared in Unit1.c */

extern MyStruct mystruct;

I think that's right. I don't have time to look over it too much right now.