Thread: extern classes

Hi all,

I have a quick question on the usage of the extern keyword. I'm trying to get a variable to be of global scope, but as it is of a custom type, I'm not sure how to use extern and Google doesn't seem to help me.

I'll provide the following code sample to try and illustrate the point better:

Code:

//In header file included at entry point

namespace custom
{

int myInt;
char myChar;
...
//global variable here
Class4 myVar;

};

#include "class1.h"
#include "class2.h" //calls myInt etc
#include "class3.h"
#include "class4.h"
#include "class5.h"

I've currently been thinking that I could open the namespace after the definition of class 4, but this seems a bit hacky. So really, this is a placement problem for which I thought of extern. Unfortunately, I can't extern myVar as it defaults to type int, and I'm not sure how to extern a class. I've tried this to no avail also:

extern Class4;
extern Class4 myVar;

I was thinking that if I can extern to an atomic type, maybe I just needed to 'tell' the compiler that Class4 was a type.

Is extern the right keyword to use? I know that this code is a bit messy, but I'm hoping that somebody may understand the problem I'm having.

Thanks for your help,
SM