C / C++ / MFC

13-Apr-07 12:16

I'm incerting the OnKeyDown function to catch keyboard events.. Problem is it never makes it to the function..

void MyDlg::OnKeyDown( UINT nChar, UINT nRepCnt, UINT nFlags )
{
AfxMessageBox(L"Got a key stroke"); <-- never pops up
CDialog::OnKeyDown( nChar, nRepCnt, nFlags );
return;
}

I've got an OnMouseWheel funtion in that works perfectly.. So I have OnKeyDown set in the same way.. Any Ideas?

Mark Salsbery13-Apr-07 12:22

13-Apr-07 12:22

Do you have a WM_KEYDOWN entry in the window class' message map?

The WM_KEYDOWN will go to the window with keyboard focus. In a dialog this may be one of the
controls in the dialog.

Mark

"Posting a VB.NET question in the C++ forum will end in tears." Chris Maunder

aquawicket13-Apr-07 12:36

13-Apr-07 12:36

yes I have ON_WM_KEYDOWN() in the message map..
hmmmm.. the function is just not hitting..

Mark Salsbery13-Apr-07 12:41

13-Apr-07 12:41

Then the window whos class your catching it in doesn't have keyboard focus.

Try using SetFocus() to set the keyboard focus to the dialog and see if it starts to work.

Mark

"Posting a VB.NET question in the C++ forum will end in tears." Chris Maunder

aquawicket13-Apr-07 12:54

13-Apr-07 12:54

I must be overiding the keyboard somewhere because I've used SetFocus(), and my OnMouseWheel works to proove it focus.. Looks like I'll have to hunt for the block.. Smile | :)

Thanks Mark..

aquawicket13-Apr-07 12:55

13-Apr-07 12:55

I must be overiding the keyboard somewhere because I've used SetFocus(), and my OnMouseWheel works to proove it's focus.. Looks like I'll have to hunt for the block.. Smile | :)

Thanks Mark..

aquawicket18-Apr-07 6:00

Is there any way to convert MFC application to C# app?

18-Apr-07 6:00

Hmm.. still having trouble with this one...
I've started a whole new dialog that I can open child dialogs within..

OnKeyDown() works until I add an object to the parent dialog or open a child dialog..
I've tried SetFocus() every which way possible.. It's just not happening..
There must be a way...

oleg6313-Apr-07 12:12

oleg63

13-Apr-07 12:12

There is an extreme push towards .NET, but no clear way to go with traditional MFC application.
Would be interesting opinion of Micrrosoft guru on that.
Just woundering, is there any way to convert MFC application to C# app or C++/CLI (rewrite option is not acceptable)?
And how traditional MFC MDI application have to be migrated/mutated towards .NET?

I'll appreciate any opinions/suggestions.

Thanks.

Re: Is there any way to convert MFC application to C# app?

Mark Salsbery13-Apr-07 12:39

Re: First Chance exception

13-Apr-07 12:39

To go to C# would be a rewrite - different framework, different language.

C++/CLI is the only language that allows you to mix unmanaged code with managed code.
While this is powerful, it also adds to the complexity. Going back and forth between managed and
unmanaged code is tricky at first - there's a learning curve there.

If you want to hold on to your MFC-based codebase, and still take advantage of the rich .NET
framework, then C++/CLI is the only way to go. From my experience this works well.

My 2 cents.
Mark

"Posting a VB.NET question in the C++ forum will end in tears." Chris Maunder

First Chance exception

namratab13-Apr-07 11:10

namratab

13-Apr-07 11:10

Hello,
I have a dialog with edit fields. and i store the data entered into them into MS SQL. Now, for data validation for CString fields, I use simple tes like
If(str=="")
{
Messagebox(something);

}
but for integer fields, VC++ 6.o automatically gives a message "please enter an integer" ,if the integer field is left blank . I get a first chance exception "0xE06D7363: Microsoft C++ Exception." and a messageBox "Please enter an integer." I guess that is because when I call UpdateData(true), there is no value for DoDataExchange. But Is there any way of disabling this message and allow me to display my own message as my application starts behaving unexpectedly after it encounters this exception. Also Could you tell me how to catch this exception thrown because of UpdateData. I could not catch it with normal CExeption * e.
Please help.

bob1697214-Apr-07 7:55

bob16972

14-Apr-07 7:55

CException only covers MFC exceptions.

If your exception is a C++ exception, you should catch the appropriate exception class or type.

If your unsure what exception class or type could be "thrown" in a particular context, then it would be advisable to research "exception handling" in MSDN as their are different types that you should get familiar with.

If you are in a hurry, you can catch "(...)" which will get just about anything, but this will possibly be frowned upon by some in the community since you basically lose the exception context and basically defeat the exception mechanism. Using "(...)" essentially turns exception handling into an overpriced "goto". To be fair, there are likely some in the community that feel "(...)" is ok to use and even handy. I find myself sitting on the fence with this one.

If the exceptional condition is avoidable, it might be better to locate where it's getting thrown, and prevent the condition in the first place. It just depends on the exception context since some exceptions are, by design, unavoidable, real world, common occurences like file and database exceptions. Some just shouldn't happen like divide by zero and memory access violations These usually indicate flawed logic and should be removed/rethought/redesigned instead of wrapping in a try/catch.

Thats just my 2 cents.

Destructor Not Getting Called

CoffeeAddict1913-Apr-07 11:09

CoffeeAddict19

13-Apr-07 11:09

I'm having a problem with a class I wrote- the destructor isn't being called for some reason and I'm getting a rather large memory leak as a result. I verified that the destructor was not being called through the use of breakpoints. Any help would be appreciated.

Here is the class defenition:

class CCharLinkedList
{
public:
	CCharLinkedList();
	~CCharLinkedList();
	void AddNodeToHead(char DataToAdd[]);
	void AddNodeToTail(char DataToAdd[]);
	bool DeleteFromHead();
	bool DeleteFromTail();
	bool CopyFromHead(char DataToCopy[]);
	bool CopyFromTail(char DataToCopy[]);
	void PrintHeadToTail();
	void PrintTailToHead();
protected:
private:
	void DeleteList();
	CharLinkedListNodeType* HeadPtr;
	CharLinkedListNodeType* TailPtr;
};

The destructor implementation:

CCharLinkedList::~CCharLinkedList()
{

	DeleteList();
	HeadPtr = NULL;
	TailPtr = NULL;
}

DeleteList():

void CCharLinkedList::DeleteList()
{
	CharLinkedListNodeType* IterationPtr = HeadPtr;
	CharLinkedListNodeType* DeletePtr = NULL;

	while(IterationPtr != NULL)
	{

		DeletePtr = IterationPtr;
		IterationPtr = IterationPtr->ForwardPtr;
		delete DeletePtr;
	}
}

The class is declared in the free store in another class header file. The other class has been working fine for a long time. So far I have been able to use the linked list to add nodes, but when it is time to call the destructor upon exiting and delete all the nodes, nothing happens.

Mark Salsbery13-Apr-07 11:23

13-Apr-07 11:23

You've shown the code for the class but it's irrelevent to the problem.

What's important is the creation and destruction of the CCharLinkedList object(s).
Are they created/destroyed with new/delete?
Are they member variables in another class? If so, when does the object of THAT class get deleted
or go out of scope?
etc...

Mark

"Posting a VB.NET question in the C++ forum will end in tears." Chris Maunder

CoffeeAddict1913-Apr-07 11:32

CoffeeAddict19

13-Apr-07 11:32

I only have one CCharLinkedList object. It is allocated on the free store (not new/delete), here:

class CRatiosWin : public CFrameWnd
{
public:
	CRatiosWin(); //default constructor
	~CRatiosWin(); //destructor
	CRatiosLogic RatiosLogic;
	bool GetNewFilePath(CString & Path);
	void PrintResults(string results);
	//accessor functions
	bool ReturnValidFilePathSet();
	//manipulator functions
	void ResetSearchDialogFlag(); //set that the search dialog has not been opened
	void SetDatabaseFilePathStatus(bool FilePathWasSet);
	void SetTimeParameterStatus(bool NewTimeParametersWereSet);
protected:
private:
	//classes
	CRatiosNewSearchDialog NewSearchDialog;
	CRatiosSearchTimeParameters TimeParametersDialog;
	CCharLinkedList TestLinkedList; :(
	//other private members
	CEdit ResultsBox;
	BOOL NewSearchDialogIsVisible; //if TRUE, the NewSearchDialog is active
	bool ValidFilePathSet;
	bool TimeParametersWereSet;
	afx_msg void OnClose();
	afx_msg void OnOpenFile();
	afx_msg void OnNewSearch();
	afx_msg void OnOpenSearch();
	afx_msg void OnAbout();
	afx_msg void OnTestList();
DECLARE_MESSAGE_MAP()
};

I loaded some text into the list by calling this at runtime:

afx_msg void CRatiosWin::OnTestList()
{
	fstream ListFileStream;
	char chLine[MAXNUMCHARS_LINKLISTNODE];
	string strLine = "";

	ListFileStream.open("list_test.txt");
	while(ListFileStream.eof() == false)
	{
		getline(ListFileStream, strLine);
		ASSERT(strLine.length() < MAXNUMCHARS_LINKLISTNODE);
		strcpy(chLine, strLine.c_str());
		TestLinkedList.AddNodeToTail(chLine);
	}
	MessageBox("Sent to file.", "Boink", MB_OK);
	ListFileStream.close();
}

All of the above worked fine. But I set breakpoints in the destructor in the previous post and none of them were reached, plus I have a big memory leak.

Mark Salsbery13-Apr-07 11:36

13-Apr-07 11:36

Cool thanks. In that case you need to look at when the CRatiosWin object is destroyed.
It is then that the CCharLinkedList member object will be destroyed.

Mark

"Posting a VB.NET question in the C++ forum will end in tears." Chris Maunder

CoffeeAddict1913-Apr-07 11:48

CoffeeAddict19

13-Apr-07 11:48

Can I assume that CRatiosWin is not getting deleted in this segment of code?

class CPRatiosApp : public CWinApp
{
	public:
	BOOL InitInstance()
	{
		_CrtSetDbgFlag( _CRTDBG_ALLOC_MEM_DF | _CRTDBG_LEAK_CHECK_DF);
		m_pMainWnd = new CRatiosWin;
		m_pMainWnd->ShowWindow(m_nCmdShow);
		m_pMainWnd->UpdateWindow();
		m_pMainWnd->SetWindowText("Ratios v0.1b");
		m_pMainWnd->MoveWindow(0,0,800,600);
	return TRUE;
	}
} CRatiosApp;

Mark Salsbery13-Apr-07 12:10

13-Apr-07 12:10

CoffeeAddict19 wrote:
Can I assume that CRatiosWin is not getting deleted in this segment of code?

Yes...correct.

I can't find where m_pMainWnd is destroyed in the MFC source...When I find it I'll post. Roll eyes | :rolleyes:

Try adding this override to your CPRatiosApp class:

virtual int ExitInstance()
{
   if (m_pMainWnd)
   {
      m_pMainWnd->DestroyWindow();
      m_pMainWnd = 0;
   }
 
   return CWinApp::ExitInstance();
}

Your destructor should be called when the m_pMainWnd->DestroyWindow(); is executed.

Mark

"Posting a VB.NET question in the C++ forum will end in tears." Chris Maunder

Mark Salsbery13-Apr-07 12:33

13-Apr-07 12:33

Ok....after reviewing MFC source -

Your destructors should get called when you close the main window (since frame windows are self-
deleting). I found no place where the app classes destroy the main window explicitly.

The ExitInstance() code I posted won't help. You'll need to close the main window before a
breakpoint in your destuctor will be called Smile | :)

Mark

"Posting a VB.NET question in the C++ forum will end in tears." Chris Maunder