Destructor Not Getting Called

[CoffeeAddict19]

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 Salsbery]

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

[CoffeeAddict19]

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 Salsbery]

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

[CoffeeAddict19]

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 Salsbery]

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. :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 Salsbery]

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 :) Mark

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

[John R Shaw]

When I learned to program we had to write stuff like this – why are you? You should be using the ‘list’ template. Some of the modern MS languages allow you to ignore the fact that if you use ‘new’ you need to supply a ‘delete’, may be that is the problem. Any thing you allocate you need to deallocate – even in C++.

INTP "Program testing can be used to show the presence of bugs, but never to show their absence."Edsger Dijkstra