shared global variables in C

Question

How can I create global variables that are shared in C? If I put it in a header file, then the linker complains that the variables are already defined. Is the only way to de

Answer 1

In the header file

header file

#ifndef SHAREFILE_INCLUDED
#define SHAREFILE_INCLUDED
#ifdef  MAIN_FILE
int global;
#else
extern int global;
#endif
#endif

In the file with the file you want the global to live:

#define MAIN_FILE
#include "share.h"

In the other files that need the extern version:

#include "share.h"