Question

As a continuation of my previous question in stackoverflow:
Getting LINK error : Extern in C++. How to access the value of a variable which is modified in File A.CPP in another file File B.CPP
IN my C++ code I want to make use of a variable “VarX” in a file “B” which is actually modified in another file “A”.
So I had a look @ the following link & used extern concept.

How do I use extern to share variables between source files?

error LNK2001: unresolved external symbol “unsigned int
VarX” (?VarX@@3IA)

My scenario is as follows:

File1.h
extern unsigned int VarX;

File2.cpp
#include File1.h
VarX = 101;

File3.cpp
#include File1.h
unsigned int temp = VarX;

IMP NOTE: In the header file File1.h there are many other structure definitions and also many othe rdefinitions apart from the Extern definition.

Can someone help me in this. How shall I read the Value of VarX which is modified in File2.cpp in another File File3.cpp.

Answer 1

You have to define VarX in global scope, which I’m assuming you’re not doing now, since otherwise it wouldn’t even compile:

//File2.cpp
#include "File1.h"
unsigned int VarX = 101;  //this has to be outside any code block or namespace
                          //or class...