changing file from C to C++

Hello!!
I'm using MFC.
I'm using a sample which has C files.
I want to put some C++ code inside, and so, I have to change the name of the files from C to C++.
To do this, I rename the files in the Explorator, and in Visual Studio, I delete the file and then add the .cpp ones.

But when I've only done this, linking errors appear:

GradientImport.obj : error LNK2001: unresolved external symbol "void __cdecl DoAbout(struct AboutRecord *)" (?DoAbout@@YAXPAUAboutRecord@@@Z)

Am I doing wrong? Do someone know what I haver to do? Maybe change something in the Settings Project, but what?



:) :) :) :) :) :)
Thanks for any help...

You should read the help of the
extern "C" directive and Mixed-Language Programming with C++.

I hope this helps

Hi....

Thanks very much for your help yesterday.
As you have told me, I have used the extern "C" symbol in my GradientImport.cpp file like this :

extern "C"{
#include "GradientImport.h"
}

The link errors have almost all disappeared, except three of them which are :


libcmt.lib(atox.obj) : error LNK2005: _atol already defined in msvcrt.lib(MSVCRT.dll)

libcmt.lib(xtoa.obj) : error LNK2005: __ultoa already defined in msvcrt.lib(MSVCRT.dll)

Creating library .\Release/GradientImport.lib and object .\Release/GradientImport.exp

libcmt.lib(crt0.obj) : error LNK2001: unresolved external symbol _main


I think that the 2 first ones must be easy to resolve, but I don’t know exactly how to do...

In my Project Settings, I have :
-for the C/C++ :
Use run-time library : Multithreaded
Calling convention : _cdecl

-for the Link :
Object/library modules : version.lib user32.lib kernel32.lib gdi32.lib msvcrt.lib
Ignore Libraries : libcmtd.lib winspool.lib comdlg32.lib advapi32.lib shell32.lib


Do someone can help me?
Is there something I am doing wrong?

And for the third error, have you got any idea?

Thanks very much for any help....




:) :) :) :) :) :)
Thanks for any help...

Hi,
You included the Multithreaded static link library (LIBCMT) and the Multithreaded dynamic link library (MSVCRT), which is one to much. Remove your link MSVCRT and it should work. Have a look in the help "C Run-Time Debug Libraries".
In general I recommend to start with the Project AppWizard and to insert own source and header files into it. That is really much faster than the other way round.

Hi...
Thanks very much for your fast answer.
I have done like you have said, and now, I have just the last link error:

libcmt.lib(crt0.obj) : error LNK2001: unresolved external symbol _main

Do you think it can be a problem in my code?
This error appears when, after including <afx.h> at the top of my GradientImport.cpp, I’m doing this...

CFileDialog fileDlg(TRUE);
fileDlg.DoModal();

If I’m removing this 2 lines, the error disappears.
Do you know what does it mean?

(I’m sorry to interrupt you in your work if so...)
And I really thank you for all your advice.
Cecile.













:) :) :) :) :) :)
Thanks for any help...

Sorry, but I don't know the details of your project. Is it Unicode? Have you made a new project with the AppWizard, as I adviced you, and integrated your cpp and h files in it? If it is a MFC app. the wizard will generate the main stuff by itself.
So long - Ralf