unresolved external

[Mark]

I'm trying to write an RAS class on windows ad RasDial's callback
function requires it to either not be a class member or for it to be
static. I went for the static option so in the header file I declared an
extern variable for the class outside of the class definition so I
could use it in the static function, like so:

#ifndef RasClientH
#define RasClientH

#include <ras.h>
#include <raserror.h>

class RasClient
{
[snip]
};

extern RasClient ras;

#endif

then in the header file for the class I will be using ras in I put:

#ifndef MainFormH
#define MainFormH

#include "RasClient.h"

[snip]

class TfrmMain : public TForm
{
[snip]
private: // User declarations
RasClient ras;
[snip]
};

#endif

but when it's linking I'm getting an error saying '[Linker Error]
Unresolved external '_ras' referenced from RASCLIENT.OBJ'. Can anyone
tell me what I'm doing wrong?

TIA

 

[Stephan Hoffmann]

I'm trying to write an RAS class on windows ad RasDial's callback
function requires it to either not be a class member or for it to be
static. I went for the static option so in the header file I declared an
extern variable for the class outside of the class definition so I
could use it in the static function, like so:

#ifndef RasClientH
#define RasClientH

#include <ras.h>
#include <raserror.h>

class RasClient
{
[snip]
};

extern RasClient ras;

This extern declaration tells the compiler that a global object
with name ras exists. It does not define (instantiate) it.
You do not instantiate it anywhere in the code you showed.
Just add

RasClient ras;

in one of your implementation files. That should solve your linker
problem, but I'm not sure it's really what you want to do.

Stephan

 

[Mark]

This extern declaration tells the compiler that a global object
with name ras exists. It does not define (instantiate) it.
You do not instantiate it anywhere in the code you showed.

[snip]

So declare it outside of a class definition?

Mark

 

[Peter_Julian]

| Stephan Hoffmann wrote:
| > This extern declaration tells the compiler that a global object
| > with name ras exists. It does not define (instantiate) it.
| > You do not instantiate it anywhere in the code you showed.
| [snip]
|
| So declare it outside of a class definition?
|
| Mark

No, define it outside the class definition.