error C2065: Undeclared identifer when using variable in another header file

Question

First header file

   //status.h file
    static int A[2] = {1,2};

And another header file

//anotherfile.h file
#include "status.h"

int GETID()
{
  return A[1];
}

I keep getting error when I compile saying A is undeclared identifier. I tried to define A as extern const int and still it did not help. In my IDE (VS2010) I can actually see the content of A when I hover over A value under GETID().

I want to use A as a global array because in my real program, A is an array contains 250 elements and I don't want to declare it more than one place in my program. What can I do in this case to make use of the array A in another header file?

Edit: A does not belong to any class where GETID() is a class function.

Answer 1

A namespace-scoped static is not a global - it's a variable with internal linkage - a copy of it will be created for each translation unit that includes the header. You have to declare it as extern and use include guards in the header:

//status.h file
#ifndef STATUS_H
#define STATUS_H
extern int A[2];
#endif

//status.cpp
#include "status.h"
int A[2] = {1,2}

Wherever you want to use A, you now just #include "status.h".

Note that int A[2] = {1,2,3}; is illegal, since you're saying A only has 2 values, but you're giving it 3.

Answer 2

There's more than one problem with your setup.

Firstly, if things were really the way you say they are, you wouldn't be getting this error from your code. Your code, the way you posted it, is perfectly compilable and there's no "undeclared identifier" problem there. The reason you are actually getting this error is circular inclusion of your header files. Directly or indirectly, you managed to include status.h into anotherfile.h and at the same time anotherfile.h into status.h. Circular header inclusion never works. Even if you resolve your main issue with the global array, you still have to get rid of circular header inclusion, since it will rear its head in some other way later.

Secondly, if you need a truly global array, i.e. one array accessible to the entire program, you have to declare it with external linkage, not as static. static declaration will produce a myriad of completely independent arrays, one for each translation unit.