shared global variables in C
In one header file (shared.h):
extern int this_is_global;In every file that you want to use this global symbol, include header containing the extern declaration:
#include "shared.h"To avoid multiple linker definitions, just one declaration of your global symbol must be present across your compilation units (e.g: shared.cpp) :
/* shared.cpp */#include "shared.h"int this_is_global;
In the header file write it with extern.And at the global scope of one of the c files declare it without extern.
In the header file
header file
#ifndef SHAREFILE_INCLUDED#define SHAREFILE_INCLUDED#ifdef MAIN_FILEint global;#elseextern int global;#endif#endifIn 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"