Trying to include an MFC dialog from a library in an MFC Application but application crashes.

Question

Trying to include an MFC dialog from a library in an MFC Application but application crashes.

AlexS13 41

Hello. I'm trying to include a dialog class from an MFC library to an MFC application. When I include them like this:

#include "CTestDlg.h"  
#include "CTestDlg.cpp"

it's working.
When I include them from properties :

C/C++ Additional Include Directories : "Path"
Linker/General/Additional Library Directories) : ".obj path"
Linker/Input/AdditionalDependencies : CTestDlg.obj

MFC Application(is built from a wizard API, it's not default MFC App. If I create a default MFC app it's working) thrown an exception.

Any idea what could be causing the problem? Thanks.

YujianYao-MSFT 4,296 Reputation points Microsoft External Staff

2021-12-16T07:21:30.247+00:00

Hi @AlexS13 ,

Could you please tell me why you chose the .obj file when linking the library file? Normally, we should choose the .lib file when linking the library.
AlexS13 41 Reputation points

2021-12-16T08:42:34.7+00:00

I know but I don't have .lib files in my folder.
YujianYao-MSFT 4,296 Reputation points Microsoft External Staff

2021-12-16T09:32:40.36+00:00

Hi @AlexS13 ,

Where did you get this library? Could you please provide the necessary code? It will help everyone to reproduce your problem.

AlexS13 41

I create a default MFC dynamic link library project, then I create a dialog class which I want include in the other project.

Here is the dialog class code that I want to use in MFC application project. I'm not sure that it is what you want to see.

#pragma once
#include "afxdialogex.h"


// CTestDlg dialog

class CTestDlg : public CDialogEx
{
    DECLARE_DYNAMIC(CTestDlg)

public:
    CTestDlg(CWnd* pParent = nullptr);   // standard constructor
    virtual ~CTestDlg();

// Dialog Data
#ifdef AFX_DESIGN_TIME
    enum { IDD = IDD_DIALOG1 };
#endif

protected:
    virtual void DoDataExchange(CDataExchange* pDX);    // DDX/DDV support

    DECLARE_MESSAGE_MAP()
};





// CTestDlg.cpp : implementation file
//

#include "pch.h"
#include "Dialogs.h"
#include "afxdialogex.h"
#include "CTestDlg.h"


// CTestDlg dialog

IMPLEMENT_DYNAMIC(CTestDlg, CDialogEx)

CTestDlg::CTestDlg(CWnd* pParent /*=nullptr*/)
    : CDialogEx(IDD_DIALOG1, pParent)
{

}

CTestDlg::~CTestDlg()
{
}

void CTestDlg::DoDataExchange(CDataExchange* pDX)
{
    CDialogEx::DoDataExchange(pDX);
}


BEGIN_MESSAGE_MAP(CTestDlg, CDialogEx)
END_MESSAGE_MAP()


// CTestDlg message handlers

RLWA32 49,551 Reputation points

2021-12-16T11:57:57.183+00:00

Its unclear to me what you hope to accomplish with this exercise.

MFC dialog classes are closely tied to their related dialog resource. The constructor of the class uses the resource identifier established when Visual Studio creates both the class and resource. This linkage between the class and the dialog resource also exists between any MFC member variables that might be added to a dialog class for controls in the dialog resource since these are connected using DDX_CONTROL in the DoDataExchange function.

When the MFC code is compiled the .obj file will contain the resource identifiers for the class. However, using that .obj file raises the question about where the dialog resource needed by this .obj file is located. If the project into which you are linking the .obj file contains the needed dialog resource then all you have accomplished is moving the compilation of a .cpp file from one project to another. Attempting to reuse the dialog's .obj file in any other project requires that you also manually create the needed dialog resource in those projects. This isn't really an efficient way to reuse an MFC dialog.

If you really want to share an MFC dialog class between MFC projects I suggest you look into using an MFC Extension DLL.

MFC extension DLLs

1 answer

Your answer

YujianYao-MSFT 4,296 Reputation points Microsoft External Staff

2021-12-16T07:21:30.247+00:00

Hi @AlexS13 ,

Could you please tell me why you chose the .obj file when linking the library file? Normally, we should choose the .lib file when linking the library.
AlexS13 41 Reputation points

2021-12-16T08:42:34.7+00:00

I know but I don't have .lib files in my folder.
YujianYao-MSFT 4,296 Reputation points Microsoft External Staff

2021-12-16T09:32:40.36+00:00

Hi @AlexS13 ,

Where did you get this library? Could you please provide the necessary code? It will help everyone to reproduce your problem.
AlexS13 41 Reputation points

2021-12-16T09:50:34.03+00:00

I create a default MFC dynamic link library project, then I create a dialog class which I want include in the other project.

Here is the dialog class code that I want to use in MFC application project. I'm not sure that it is what you want to see.

#pragma once #include "afxdialogex.h" // CTestDlg dialog class CTestDlg : public CDialogEx { DECLARE_DYNAMIC(CTestDlg) public: CTestDlg(CWnd* pParent = nullptr); // standard constructor virtual ~CTestDlg(); // Dialog Data #ifdef AFX_DESIGN_TIME enum { IDD = IDD_DIALOG1 }; #endif protected: virtual void DoDataExchange(CDataExchange* pDX); // DDX/DDV support DECLARE_MESSAGE_MAP() }; // CTestDlg.cpp : implementation file // #include "pch.h" #include "Dialogs.h" #include "afxdialogex.h" #include "CTestDlg.h" // CTestDlg dialog IMPLEMENT_DYNAMIC(CTestDlg, CDialogEx) CTestDlg::CTestDlg(CWnd* pParent /*=nullptr*/) : CDialogEx(IDD_DIALOG1, pParent) { } CTestDlg::~CTestDlg() { } void CTestDlg::DoDataExchange(CDataExchange* pDX) { CDialogEx::DoDataExchange(pDX); } BEGIN_MESSAGE_MAP(CTestDlg, CDialogEx) END_MESSAGE_MAP() // CTestDlg message handlers
RLWA32 49,551 Reputation points

2021-12-16T11:57:57.183+00:00

Its unclear to me what you hope to accomplish with this exercise.

MFC dialog classes are closely tied to their related dialog resource. The constructor of the class uses the resource identifier established when Visual Studio creates both the class and resource. This linkage between the class and the dialog resource also exists between any MFC member variables that might be added to a dialog class for controls in the dialog resource since these are connected using DDX_CONTROL in the DoDataExchange function.

When the MFC code is compiled the .obj file will contain the resource identifiers for the class. However, using that .obj file raises the question about where the dialog resource needed by this .obj file is located. If the project into which you are linking the .obj file contains the needed dialog resource then all you have accomplished is moving the compilation of a .cpp file from one project to another. Attempting to reuse the dialog's .obj file in any other project requires that you also manually create the needed dialog resource in those projects. This isn't really an efficient way to reuse an MFC dialog.

If you really want to share an MFC dialog class between MFC projects I suggest you look into using an MFC Extension DLL.

MFC extension DLLs

Answer 1

Flaviu_ 1,031

Have you did a debugging in your code ? When exactly take happen that error ?

AlexS13 41 Reputation points

2021-12-15T15:06:42.823+00:00

I can't really understand because it goes to API files.
AlexS13 41 Reputation points

2021-12-20T09:36:57.493+00:00
Maybe it's something related to resource because the exception is thrown in this:

_AFXWIN_INLINE HINSTANCE AFXAPI AfxGetResourceHandle() { ASSERT(afxCurrentResourceHandle != NULL);
RLWA32 49,551 Reputation points

2021-12-20T10:15:01.783+00:00

MFC Application(is built from a wizard API, it's not default MFC App. If I create a default MFC app it's working) thrown an exception.

What's the difference between an MFC application created by the new MFC Application wizard and a default MFC App?

OK, so an assertion failed. Posting two lines of code without any context doesn't tell us much.

If you want detailed debugging assistance you should share a complete MFC solution that reliably reproduces the problem.

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Trying to include an MFC dialog from a library in an MFC Application but application crashes.

1 answer

Your answer