Calling a variable ?

[mark]

How does one call a variable defined in a class defined in file1.cpp
from another file file2.cpp. Or can one call a class from a different
file ?

(Besides the standard way to define the variable in a header file and
include this header file where required)

[Ian]

mark wrote:

How does one call a variable defined in a class defined in file1.cpp
from another file file2.cpp. Or can one call a class from a different
file ?
Call a variable?
(Besides the standard way to define the variable in a header file and
include this header file where required)

Why would you want to do it another way?

You can provide a prototype in the compilation unit you want to make the
call from but this is tedious and a maintenance headache.

Ian

[Siemel Naran]

"mark" <ma*********@yahoo.com> wrote in message

How does one call a variable defined in a class defined in file1.cpp
from another file file2.cpp. Or can one call a class from a different
file ?
In file1.h declare the variable as extern. In file2.cpp include file1.h.

// file1.h
#if !defined(include_file1)
#define include_file1
extern int variable;
#endif

// file1.cpp
#include "file1.h"
int variable = 0;

// file2.cpp
#include "file2.h"
#include "file1.h" // variable
void f() {
++variable;
}

(Besides the standard way to define the variable in a header file and
include this header file where required)

Is what I describe the standard? Why do you not want to do this?