Well, I have 3 files file1.cpp file2.cpp and shared header head.hpp I want to create a class class CTest { public: void Hello(void); int Value; }; in file head.hpp and access this class from any file...how to create it ? I allways get error. ERROR: class CTest is allready defined in module blahblahblah or when i use extern ERROR: unresolved external any ideas ? thax !

All of you header files need to use preprocessor directives to prevent this problem ... here''s how:

at the top of your header put

  #ifndef MY_FILE_H#define MY_FILE_H  

and at the bottom of your file put

  #endif  

and that shuold do it ...

note that you need to replace MY_FILE_H with a unique name for each file ... my convention is this ... if my file names are:

SharedSerialManager.h and SharedSerialAgent.h

my defines use the names

SHARED_SERIAL_MANAGER_H and SHARED_SERIAL_AGENT_H

which is easy to read ... and is nearly guaranteed not to overlap any other defines.

good luck.

Thanx for the reply, but I still have the problem...

I''m trying to do everything! 2 files, shared header with code:

#ifndef __FILE_H__
#define __FILE_H__

class CTest {
public:
void XXX(void);
int DDD;
};

#endif

and in file 1 is:

#include <windows.h>
#include "FILE.H"
CTest *Test;
int WINAPI WinMain(HINSTANCE hI, HINSTANCE pI, LPSTR Cmd, int S)
{
Test->DDD = 10;
Test->XXX();
return 0;
}

and in file 2 is:

#include <windows.h>
#include "FILE.H"
CTest *Test;

void CTest::XXX(void)
{
if (Test->DDD==10) MessageBox(NULL,"OK","OK",MB_OK);
return;
}

THIS SHOULD WORK RIGHT...but an error occures:
ERROR: class _CTest was already defined in module ...
or when I try to use extern:
ERROR: unresolved external class _CTest ...

i don''t know what to do ! I''ve tried crazy things and I''ve made this work one time, but I sayed "Program has rised an illegal instriction" (or such - I don''t know - i don''t have english windows but you certainly know what i mean ... )
PLEASE HELP ! THANKS !!!

File.h:

    // #define etc.class CTest{};extern CTest* Test;  

In File.cpp:

        #include "File.h"CTest* Test;// ...  

In Main.cpp:

  #include "File.h"void main(){   Test.XXX();}  

You only want "extern" in the header file, and you only want to declare the CTest object once - in the source file (.cpp) that belongs to the header.

HTH, Steve

Edited by - Steveyboy on February 8, 2002 3:35:46 PM