mfc static member objects 1

[EEEeee]

Hi All,

Why is it that within a class declaration I can write :

static CString str;

but I can't write :

static CObList lst;

without getting a link error ?

Any help greatly appreciated.

Regards,

EEEeee...

 

[IonelBurtan]

I had tried the:
#include <afxcoll.h> //in stdafx.h

class xxxx{
...
static CObList lst;
...
};

And I got no link error.
I tried this inside a MFC EXE project.

Maybe this helps you,s-)

Blessed is he who in the name of justice and good will, shepards the week through the valley of darknees...

http://home.domaindlx.com/ionelb

 

[EEEeee]

OK, here's what I have :

class CRecorder
{
public:
CRecorder(DEVICE *pDevice);
virtual ~CRecorder();

static CObList FreeDevs;
static CObList BusyDevs;

// Various other member declarations.
};

The app is a console app with MFC support (to be turned into a service once complete & tested).

A number of CRecorder instances are to be created at run time.

The errors I receive are as follows :

Main.obj : error LNK2001: unresolved external symbol &quot;public: static class CObList CRecorder::BusyDevs&quot;
Main.obj : error LNK2001: unresolved external symbol &quot;public: static class CObList CRecorder::FreeDevs&quot;

I have afxcoll.h included, no idea why the unresolved externals, if I remove the static keyword everything links fine.

Please help !!!

Regards,

EEEeee...

 

[Cagliostro]

It is because you must initialize the static variable in that object:

class x
{
public:
static int c;
};


int x::c=1;//if you don't do it, you'll get a linker error


int main()
{
x t;
t.c=0;
return 0;
}

John Fill

ivfmd@mail.md

 

[EEEeee]

It's not a static var though, it's a static object.

Further to this, if I add :

static CString str;

into the class definition and compile - no problemo, however as soon as I reference CRecorder::str I get the same link error as before.

R's,

EEEeee...

 

[IonelBurtan]

My project still work. I have VisualC++ 6.0 with SP3 on NT4.0.

I had created a new empty project of type console aplication, I have chosen the last option with mfc support and it works. Below are my .h file and stdafx.h file:

#include <afxcoll.h>
class CRecorder
{
public:
CRecorder();
virtual ~CRecorder();

static CObList FreeDevs;
static CObList BusyDevs;
};

//stdafx.h
#define VC_EXTRALEAN // Exclude rarely-used stuff from Windows headers

#include <afx.h>
#include <afxwin.h> // MFC core and standard components
#include <afxext.h> // MFC extensions
#include <afxdtctl.h> // MFC support for Internet Explorer 4 Common Controls
#ifndef _AFX_NO_AFXCMN_SUPPORT
#include <afxcmn.h> // MFC support for Windows Common Controls
#endif // _AFX_NO_AFXCMN_SUPPORT

#include <iostream>
////////////////////////

You should have make your project work, by now.
Hope this is getting you out of trouble. s-)

Blessed is he who in the name of justice and good will, shepards the week through the valley of darknees...

http://home.domaindlx.com/ionelb

 

[Cagliostro]

do what I sayd. It sure will work. John Fill

ivfmd@mail.md

 

[EEEeee]

Thanks BurtanI, does your example link when you reference the static members from other code ?

R's,

E.

 

[EEEeee]

Thanks JohnFill, with a simple...

CObList CRecorder::BusyDevs;

...all is now well with my world.

R's,

E.