Re: Heap corruption. - C / C++ / MFC Discussion Boards

Re: Heap corruption.

Polite Programmer3-Jun-07 1:57

Polite Programmer

3-Jun-07 1:57

One more thing, The GlobalAlloc() and GlobalFree() also act the similar way as the malloc() does.

Polite Programmer

More Object Oriented then C#

Re: Heap corruption.

Gary R. Wheeler3-Jun-07 1:59

Gary R. Wheeler

3-Jun-07 1:59

Hmm. Myself, I always prefer the new/delete approach over malloc()/free(), because these sorts of issues don't tend to arise as often.

There isn't a significant difference between the performance of the two approaches. Is there any particular reason you're using malloc()?

Software Zen: delete this;

Fold With Us![^]

Re: Heap corruption.

CPallini3-Jun-07 3:47

CPallini

3-Jun-07 3:47

Because he wants to use pure C.

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

Re: Heap corruption.

Matthew Faithfull3-Jun-07 3:08

Matthew Faithfull

3-Jun-07 3:08

You'll get those heap corruption messages in Debug only because in debug the CRT ( C RunTime library ) is checking up on you and picking up the mismatch between malloc and delete. The Debug CRT new adds extra info to the allocation to indicate what sort of allocation it is, i.e. you did it or it's internal to the CRT or thread specific or whatever. When you do the delete, it checks this info to make sure it matches but because you called malloc the extra info didn't get initialised and it's either wrong or missing. In Release the extra info and checking is cut for performance so you don't get the errors.

Conclusion: For a happy life you really do need to match malloc with free and new with delete Wink | ;)

Nothing is exactly what it seems but everything with seems can be unpicked.

Re: Heap corruption.

CPallini3-Jun-07 3:48

CPallini

3-Jun-07 3:48

Try to post the relevant code.
Smile | :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

Re: Heap corruption.

Stephen Hewitt3-Jun-07 14:08

Stephen Hewitt

3-Jun-07 14:08

I give the following advice about once a month (more recently); it often helps me track down the nastier heap errors:

Try enabling the page heap[^] for your process. Follow these steps:
1. Download and install WinDBG[^].
2. Select “Start”->“All Programs”->“Debugging Tools for Windows”->“Global Flags”.
3. Select the “Image File” tab.
4. In the “Image: (TAB to refresh)” edit control enter the name of your app then press TAB. Just the name with the extension; not the full path.
5. Tick the following:
- “Enable page heap”
- “Enable heap tail checking”
- “Enable heap free checking”
- “Enable heap parameter checking”
- “Enable heap validation on call”
- “Create user mode stack trace database”
6. Press “Apply”.
7. Debug your application. Any debugger will do but with WinDBG you have access to the stack traces of allocations via the !heap –p –a command, for example. When a heap problem is detected a breakpoint will be generated.
8. When done un-tick all the options you ticked, press “Apply” then dismiss GFlags. This step is important as if it’s skipped all applications named as entered in step 4 will run with the page heap enabled.

Note that when using the page heap your application will run much slower than normal and consume way more memory. It’s good to have a beefy machine to do such tests; and such tests should be ran regularly on all applications you develop as part of regular testing activities. If I find a part of my application that’s too slow with the page heap enabled I optimize the memory allocation in that region.

Steve

Re: Heap corruption.

Polite Programmer3-Jun-07 20:00

Polite Programmer

3-Jun-07 20:00

Reason for using malloc() stuff is that I want to be pure in C.

What I am doing?

1.... I want to write a pure C control to teach myself internals of Win32 Message Architecture.
2... When done with this, I will burry that control (a simple button control yet...) into a DLL.
3... When done with the DLL, I will try to write a COM wrapper around it that too in pure C to check whether it can be used with VB, and .NET.

Friends one more thing... my every malloc() is having a free() but still facing problem. And one of our felllows is very much right, the problem only occurs in Debug sessions.

Here is the source code.

Please consider the following functions specially.... Are they correct?

a) AllocateButtonInfoFor()
b) DeleteButtonInfo()
c) OnNCCreate()
d) OnSetText()

First is the ButtonControl.h
============================

#ifndef __BUTTON_CONTROL_H__<br />
#define __BUTTON_CONTROL_H__<br />
#include "stdafx.h"<br />
<br />
#define BUTTON_CONTROL_CLASS			TEXT("BUTTON_CONTROL_safsf")<br />
<br />
<br />
#ifdef __INCLUDE_BUTTONCONTROL_PRIVATES__<br />
<br />
/* Depicts the state of the button */<br />
typedef enum tagBUTTONSTATE<br />
{<br />
	NORMAL = 2,<br />
	HOVER,<br />
	PRESSED,<br />
	DISABLED<br />
<br />
} BUTTONSTATE;<br />
<br />
/* Structure to hold the information of the button*/<br />
typedef struct tagBUTTONINFO<br />
{<br />
//	HWND hWnd;							/* Handle of the button itself */<br />
	TCHAR * szText;						/* The caption of button */<br />
	int nTextLength;					/* Length of caption */<br />
	HPEN borderColor;					/* The outline color */<br />
	COLORREF textColor;					/* The Text Color of the button */<br />
	HBRUSH backColor;					/* The background color of the button */<br />
	HFONT font;							/* The font of the text */<br />
	HPEN borderColorPressed;			/* The border color in pressed form*/<br />
	COLORREF textColorPressed;			/* The text color in pressed form */<br />
	HBRUSH backColorPressed;			/* The back color in pressed form */<br />
	HFONT fontPressed;					/* The font in pressed form */<br />
	HPEN borderColorHover;				/* The border color in hover form*/<br />
	COLORREF textColorHover;			/* The text color in hover form */<br />
	HBRUSH backColorHover;				/* The back color in hover form */<br />
	HFONT fontHover;					/* The font in hover form */<br />
<br />
	BUTTONSTATE state;					/* The state of the button */<br />
<br />
} BUTTONINFO, * PBUTTONINFO;<br />
<br />
/* ButtonInfo Allocation */<br />
//HANDLE	CreateHeapIfNeeded();<br />
//BOOL	DestroyHeapIfNeeded(HANDLE);<br />
<br />
PBUTTONINFO AllocateButtonInfoFor(HWND hWnd);<br />
PBUTTONINFO PickButtonInfo(HWND hWnd);<br />
BOOL DropButtonInfo(HWND hWnd);<br />
void DeleteButtonInfo(HWND hWnd);<br />
void SetButtonDefaults(HWND hWnd, PBUTTONINFO pButtonInfo);<br />
<br />
void DrawButton(HWND hWnd, PBUTTONINFO pButtonInfo, HDC hdc);<br />
<br />
/* The window procedure. */<br />
LRESULT CALLBACK ButtonProc(HWND, UINT, WPARAM, LPARAM);<br />
<br />
/* The Button Event Handlers */<br />
<br />
<br />
BOOL	OnNCCreate(HWND hwnd, LPCREATESTRUCT lpCreateStruct);<br />
void	OnNCDestroy(HWND);<br />
void	OnPaint(HWND);<br />
void	OnInitButton(HWND hWnd);<br />
void	OnMouseButtonDown(HWND hWnd, int x, int y);<br />
void	OnMouseButtonUp(HWND hWnd, int x, int y);<br />
INT		OnGetText(HWND, int, LPTSTR);<br />
INT		OnGetTextLength(HWND);<br />
BOOL	OnSetText(HWND hWnd, LPCTSTR);<br />
<br />
//void	OnDestroy(HWND);<br />
/*<br />
BOOL	OnCreate(HWND, LPCREATESTRUCT);<br />
<br />
<br />
void	OnEnable(HWND, BOOL);<br />
<br />
<br />
<br />
HFONT	OnGetFont(HWND);<br />
<br />
void	OnSetFont(HWND hWnd, HFONT hFont, BOOL fRedraw);<br />
void	OnMouseButtonDown(HWND, int nMask, int x, int y);<br />
void	OnMouseButtonUp(HWND, int nMask, int x, int y);<br />
*/<br />
#endif /* __INCLUDE_BUTTONCONTROL_PRIVATES__ */<br />
<br />
// The Button Messages used to set and get properties.<br />
<br />
#define BCM_SETBORDERPEN				WM_USER + 10	/* WPARAM	= HPEN			*/<br />
#define BCM_GETBORDERPEN				WM_USER + 11	/* Return	= HPEN			*/<br />
#define BCM_SETCAPTIONCOLOR				WM_USER + 12	/* WPARAM	= COLORREF		*/<br />
#define BCM_GETCAPTIONCOLOR				WM_USER + 13	/* Return	= COLORREF		*/<br />
#define BCM_SETBACKGNDBRUSH				WM_USER + 14	/* WPARAM	= HBRUSH		*/<br />
#define BCM_GETBACKGNDBRUSH				WM_USER + 15	/* Return	= HBRUSH		*/<br />
#define BCM_SETBUTTONSTATE				WM_USER + 16	/* WPARAM	= BUTTONSTATE	*/<br />
#define BCM_GETBUTTONSTATE				WM_USER + 17	/* Return	= BUTTONSTATE	*/<br />
#define BCM_INITBUTTON					WM_USER + 18	/* NULL */<br />
<br />
// Initializes the button control<br />
HRESULT InitButtonControl(HINSTANCE hInstance);<br />
#endif /*__BUTTON_CONTROL_H__*/

Second is ButtonControl.cpp
===========================

#include "stdafx.h"<br />
#define __INCLUDE_BUTTONCONTROL_PRIVATES__		/* So that we may have private functions. */<br />
#include "ButtonControl.h"<br />
<br />
//static ULONG gButtonCount = 0;<br />
//static HANDLE ghHeap = NULL;<br />
<br />
/***********************************************************************\<br />
FUNCTION:			InitButtonControl<br />
PURPOSE:			Registers the button class<br />
ARGS:				HINSTANCE hInstance<br />
RETURN:				The result of the registration<br />
\***********************************************************************/<br />
HRESULT InitButtonControl(HINSTANCE hInstance)<br />
{<br />
	WNDCLASSEX wc;<br />
<br />
	wc.cbClsExtra			= 0;<br />
	wc.cbSize				= sizeof(WNDCLASSEX);<br />
	wc.cbWndExtra			= 0;<br />
	wc.hbrBackground		= (HBRUSH)(COLOR_WINDOW + 1);<br />
	wc.hCursor				= LoadCursor(NULL, IDC_ARROW);<br />
	wc.hIcon				= LoadIcon(NULL, IDI_APPLICATION);<br />
	wc.hIconSm				= LoadIcon(NULL, IDI_APPLICATION);<br />
	wc.hInstance			= hInstance;<br />
	wc.lpfnWndProc			= ButtonProc;<br />
	wc.lpszClassName		= BUTTON_CONTROL_CLASS;<br />
	wc.lpszMenuName			= NULL;<br />
	wc.style				= CS_HREDRAW | CS_VREDRAW |<br />
								CS_GLOBALCLASS;<br />
	<br />
	//HeapCreate(HC<br />
	<br />
	//DWORD dwErr = GetLastError();<br />
	return RegisterClassEx(&wc);<br />
}<br />
<br />
<br />
<br />
/***********************************************************************\<br />
FUNCTION:			AllocateButtonInfoFor<br />
PURPOSE:			Allocate and attaches the BUTTONINFO structure<br />
ARGS:				Handle to the button<br />
RETURN:				Pointer to allocated BUTTONINFO structure<br />
\***********************************************************************/<br />
PBUTTONINFO AllocateButtonInfoFor(HWND hWnd)<br />
{<br />
	if(!hWnd)<br />
		return NULL;<br />
<br />
	//PBUTTONINFO hMem = (PBUTTONINFO) GlobalAlloc(GMEM_FIXED, sizeof(BUTTONINFO));<br />
	PBUTTONINFO hMem = (PBUTTONINFO) malloc(sizeof(BUTTONINFO));<br />
	//PBUTTONINFO hMem = new BUTTONINFO();<br />
<br />
	if(!hMem)<br />
		return NULL;<br />
<br />
	SetWindowLong(hWnd, GWL_USERDATA, (LONG)hMem);<br />
<br />
	SetButtonDefaults(hWnd, hMem);<br />
<br />
	return hMem;<br />
<br />
<br />
}<br />
<br />
<br />
/***********************************************************************\<br />
FUNCTION:			PickButtonInfo<br />
PURPOSE:			Extracts the BUTTONINFO structure from the button<br />
ARGS:				Handle to the button<br />
RETURN:				Pointer to the extracted BUTTONINFO Structure<br />
\***********************************************************************/<br />
PBUTTONINFO PickButtonInfo(HWND hWnd)<br />
{<br />
	if(!hWnd)<br />
		return NULL;<br />
<br />
	PBUTTONINFO hMem = (PBUTTONINFO) GetWindowLong(hWnd, GWL_USERDATA);<br />
<br />
	if(!hMem)<br />
		return NULL;<br />
<br />
	//PBUTTONINFO pButtonInfo = (PBUTTONINFO) GlobalLock(hMem);<br />
<br />
	DWORD dw = GetLastError();<br />
<br />
	return hMem;<br />
<br />
<br />
}<br />
<br />
/***********************************************************************\<br />
FUNCTION:			DropButtonInfo<br />
PURPOSE:			Locks the BUTTONINFO structure of the given control<br />
ARGS:				Handle to the control<br />
RETURN:				Succuss status of the operation<br />
\***********************************************************************/<br />
BOOL DropButtonInfo(HWND hWnd)<br />
{<br />
	if(!hWnd)<br />
		return FALSE;<br />
<br />
	PBUTTONINFO hMem = (PBUTTONINFO)GetWindowLong(hWnd, GWL_USERDATA);<br />
<br />
	if(!hMem)<br />
		return FALSE;<br />
<br />
	return TRUE;<br />
<br />
<br />
}<br />
<br />
/***********************************************************************\<br />
FUNCTION:			DeleteButtonInfo<br />
PURPOSE:			Deletes the BUTTONINFO structure<br />
ARGS:				Handle to the button structure<br />
RETURN:				None<br />
\***********************************************************************/<br />
void DeleteButtonInfo(HWND hWnd)<br />
{<br />
	if(!hWnd)<br />
		return;<br />
<br />
	PBUTTONINFO pButtonInfo = PickButtonInfo(hWnd);<br />
	<br />
	if(!pButtonInfo)<br />
		return;<br />
<br />
	DeleteObject((HGDIOBJ)pButtonInfo->backColor);<br />
	DeleteObject((HGDIOBJ)pButtonInfo->borderColor);<br />
	DeleteObject((HGDIOBJ)pButtonInfo->font);<br />
	//GlobalFree((HGLOBAL)pButtonInfo->szText);<br />
	//_free_dbg((void *) pButtonInfo->szText, _NORMAL_BLOCK);<br />
	//delete [] pButtonInfo->szText;<br />
<br />
	if(pButtonInfo->szText != NULL)<br />
		free((void *)pButtonInfo->szText);<br />
	<br />
<br />
	DeleteObject((HGDIOBJ)pButtonInfo->backColorPressed);<br />
	DeleteObject((HGDIOBJ)pButtonInfo->borderColorPressed);<br />
	DeleteObject((HGDIOBJ)pButtonInfo->fontPressed);<br />
<br />
<br />
	//GlobalFree((HGLOBAL)GetWindowLong(hWnd, GWL_USERDATA));<br />
	void * hMem = (void *) GetWindowLong(hWnd, GWL_USERDATA);<br />
<br />
	if(hMem != NULL)<br />
		free((void *)GetWindowLong(hWnd, GWL_USERDATA));<br />
	//delete (PBUTTONINFO)GetWindowLong(hWnd, GWL_USERDATA);<br />
}<br />
<br />
/***********************************************************************\<br />
FUNCTION:			SetButtonDefaults<br />
PURPOSE:			Sets the default values for the button<br />
ARGS:				Handle to button<br />
RETURN:				None<br />
\***********************************************************************/<br />
void SetButtonDefaults(HWND hWnd, PBUTTONINFO pButtonInfo)<br />
{<br />
	//PBUTTONINFO pButtonInfo = PickButtonInfo(hWnd);<br />
<br />
	if(!pButtonInfo)<br />
		return;<br />
<br />
	//HWND hWnd = pButtonInfo->hWnd;<br />
<br />
	ZeroMemory((PVOID)pButtonInfo, sizeof(BUTTONINFO));<br />
<br />
	pButtonInfo->backColor		= (HBRUSH) CreateSolidBrush(RGB(123,123,123));<br />
	pButtonInfo->borderColor	= (HPEN) CreatePen(PS_SOLID, 1, RGB(200,10,19));<br />
	pButtonInfo->font			= (HFONT) GetStockFont(ANSI_VAR_FONT);<br />
	pButtonInfo->textColor		= RGB(255, 255, 255);<br />
	pButtonInfo->state			= NORMAL;<br />
	pButtonInfo->szText			= NULL;<br />
	//lstrcpy(pButtonInfo->szText, TEXT("Flat Button"));<br />
	pButtonInfo->nTextLength	= 0;<br />
<br />
	pButtonInfo->backColorPressed	= CreateSolidBrush(RGB(200,180,150));<br />
	pButtonInfo->borderColorPressed	= (HPEN) GetStockObject(BLACK_PEN);<br />
	pButtonInfo->fontPressed		= (HFONT)GetStockObject(ANSI_VAR_FONT);<br />
	pButtonInfo->textColorPressed	= RGB(0,0,0);<br />
	<br />
<br />
	/* Set the background color */<br />
//	pButtonInfo->hWnd;<br />
	//SetClassLong(hWnd, GCL_HBRBACKGROUND, (LONG)pButtonInfo->backColor);<br />
<br />
	//DropButtonInfo(hWnd);<br />
}<br />
<br />
/***********************************************************************\<br />
FUNCTION:			DrawButton<br />
PURPOSE:			Draws the button according to the button status<br />
ARGS:				HWND: Handle to the button<br />
					HDC Device Context. If NULL, obtained automatically.<br />
					But in case of WM_PAINT, it should not be null.<br />
RETURN:				None<br />
\***********************************************************************/<br />
void DrawButton(HWND hWnd, PBUTTONINFO pButtonInfo, HDC hdc)<br />
{<br />
	static TCHAR szBuffer[256];<br />
<br />
	if(!pButtonInfo)<br />
		return;<br />
<br />
	//HWND hWnd = pButtonInfo->hWnd;<br />
<br />
	if(!IsWindow(hWnd))<br />
		return;<br />
<br />
	<br />
	HDC hDC = NULL;<br />
<br />
	if(hdc == NULL)<br />
		hDC = GetDC(hWnd);<br />
	else<br />
		hDC = hdc;<br />
<br />
	// PBUTTONINFO pButtonInfo = PickButtonInfo(hWnd);<br />
<br />
	RECT rect;<br />
<br />
	GetClientRect(hWnd, &rect);<br />
	<br />
	if(pButtonInfo->state == NORMAL)<br />
	{<br />
		/* Draw Normal */<br />
			/* Draw Hover State */<br />
		<br />
		SelectObject(hDC, (HGDIOBJ)pButtonInfo->backColor);<br />
		SelectObject(hDC, (HGDIOBJ)pButtonInfo->borderColor);<br />
		SetTextColor(hDC, pButtonInfo->textColor);<br />
		SetBkMode(hDC, TRANSPARENT);<br />
<br />
		/* Fill the rectangle with the background color */<br />
		FillRect(hDC, &rect, pButtonInfo->backColor);<br />
<br />
<br />
	}<br />
<br />
	if(pButtonInfo->state == HOVER)<br />
	{<br />
	<br />
	}<br />
<br />
	if(pButtonInfo->state == PRESSED)<br />
	{<br />
		// Draw Pressed<br />
		SelectObject(hDC, (HGDIOBJ)pButtonInfo->backColorPressed);<br />
		SelectObject(hDC, (HGDIOBJ)pButtonInfo->borderColorPressed);<br />
		SetTextColor(hDC, pButtonInfo->textColorPressed);<br />
		SetBkMode(hDC, TRANSPARENT);<br />
<br />
		FillRect(hDC, &rect, pButtonInfo->backColorPressed);<br />
	}<br />
<br />
	if(pButtonInfo->state == DISABLED)<br />
	{<br />
		// Draw Disabled<br />
	}<br />
<br />
		<br />
<br />
		Rectangle(hDC, rect.left, rect.top, rect.right, rect.bottom);<br />
		<br />
		<br />
		//int i = GetWindowText(hWnd, szBuffer, 256);<br />
<br />
		<br />
		DrawText(hDC, pButtonInfo->szText,<br />
					  pButtonInfo->nTextLength,<br />
					  &rect,<br />
					  DT_SINGLELINE | DT_VCENTER | DT_CENTER);<br />
<br />
		<br />
<br />
		/*<br />
		DrawText(hDC, szBuffer,<br />
					  i,<br />
					  &rect,<br />
					  DT_SINGLELINE | DT_VCENTER | DT_CENTER);<br />
	   */<br />
<br />
<br />
<br />
	if(hdc == NULL)<br />
		ReleaseDC(hWnd, hDC);<br />
<br />
}<br />
<br />
/***********************************************************************\<br />
FUNCTION:			ButtonProc<br />
PURPOSE:			Handles the messages for the button<br />
ARGS:				Same as to WndProc<br />
<br />
HANDLES:<br />
WM_PAINT<br />
<br />
<br />
WM_ENABLE<br />
<br />
WM_CREATE<br />
WM_NCCREATE<br />
WM_NCDESTROY<br />
<br />
WM_SIZE<br />
WM_MOVE<br />
WM_MOVING<br />
WM_WINDOWPOSCHANGED<br />
WM_WINDOWPOSCHANGING<br />
<br />
WM_LBUTTONDOWN<br />
WM_LBUTTONUP<br />
<br />
WM_GETTEXT<br />
WM_SETTEXT<br />
WM_GETTEXTLENGH<br />
WM_SETFONT<br />
WM_GETFONT<br />
WM_GETMINMAXINFO<br />
<br />
BCM_SETBORDERPEN<br />
BCM_GETBORDERPEN<br />
BCM_SETCAPTIONCOLOR<br />
BCM_GETCAPTIONCOLOR<br />
BCM_SETBACKGNDBRUSH<br />
BCM_GETBACKGNDBRUSH<br />
BCM_SETBUTTONSTATE<br />
BCM_GETBUTTONSTATE<br />
<br />
\***********************************************************************/<br />
LRESULT CALLBACK ButtonProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam)<br />
{<br />
	switch(msg)<br />
	{<br />
		//HANDLE_WM_NCCREATE(hWnd, wParam, lParam, OnNCCreate);<br />
	/*=======================================================<br />
			WM_NCCREATE<br />
	  ======================================================*/<br />
	case WM_NCCREATE:<br />
		{<br />
			return (LRESULT) OnNCCreate(hWnd, (LPCREATESTRUCT)lParam);<br />
		}<br />
<br />
	case WM_CREATE:<br />
		{<br />
			PostMessage(hWnd, BCM_INITBUTTON, 0, 0);<br />
			return TRUE;<br />
		}<br />
<br />
	case BCM_INITBUTTON:<br />
		{<br />
			//OnInitButton(hWnd);<br />
			return 0;<br />
		}<br />
	/*=======================================================<br />
			WM_NCDESTROY<br />
	  ======================================================*/<br />
	case WM_DESTROY:<br />
		{<br />
			OnNCDestroy(hWnd);<br />
			return 0;<br />
		}<br />
<br />
	/*=======================================================<br />
		WM_PAINT<br />
	 ======================================================*/<br />
	case WM_PAINT:<br />
		{<br />
			OnPaint(hWnd);<br />
			/*<br />
			PAINTSTRUCT ps;<br />
			HDC hdc = BeginPaint(hWnd, &ps);<br />
			RECT rect;<br />
			GetClientRect(hWnd, &rect);<br />
			Rectangle(hdc, rect.left, rect.top, rect.right, rect.bottom);<br />
			EndPaint(hWnd, &ps);<br />
			*/<br />
			return 0;<br />
		}<br />
<br />
	/*=======================================================<br />
		WM_LBUTTONDOWN<br />
	 ======================================================*/<br />
	case WM_LBUTTONDOWN:<br />
	case WM_RBUTTONDOWN:<br />
		{<br />
			OnMouseButtonDown(hWnd, LOWORD(lParam), HIWORD(lParam));<br />
			return 0;<br />
		}<br />
<br />
	/*=======================================================<br />
		WM_LBUTTONUP<br />
	 ======================================================*/<br />
	case WM_LBUTTONUP:<br />
	case WM_RBUTTONUP:<br />
		{<br />
			OnMouseButtonUp(hWnd, LOWORD(lParam), HIWORD(lParam));<br />
			return 0;<br />
		}<br />
<br />
	/*=======================================================<br />
		WM_GETTEXT<br />
	 ======================================================*/<br />
	case WM_GETTEXT:<br />
		{<br />
			return OnGetText(hWnd, (int)wParam, (LPTSTR)lParam);<br />
		}<br />
<br />
	/*=======================================================<br />
		WM_GETTEXTLENGTH<br />
	 ======================================================*/<br />
	case WM_GETTEXTLENGTH:<br />
		{<br />
			return OnGetTextLength(hWnd);<br />
		}<br />
<br />
	/*=======================================================<br />
		WM_SETTEXT<br />
	 ======================================================*/<br />
	case WM_SETTEXT:<br />
		{<br />
			return OnSetText(hWnd, (LPCTSTR)lParam);<br />
		}<br />
<br />
	<br />
/*		<br />
		HANDLE_WM_CREATE(hWnd, wParam, lParam, OnCreate);<br />
		HANDLE_WM_DESTROY(hWnd, wParam, lParam, OnDestroy);<br />
		HANDLE_WM_NCDESTROY(hWnd, wParam, lParam, OnNCDestroy);<br />
<br />
		HANDLE_WM_PAINT(hWnd, wParam, lParam, OnPaint);<br />
<br />
		HANDLE_WM_ENABLE(hWnd, wParam,lParam, OnEnable);<br />
<br />
		<br />
		HANDLE_WM_GETTEXT(hWnd, wParam, lParam, OnGetText);<br />
		HANDLE_WM_GETTEXTLENGTH(hWnd, wParam, lParam, OnGetTextLength);<br />
		HANDLE_WM_GETFONT(hWnd, wParam, lParam, OnGetFont);<br />
<br />
		HANDLE_WM_SETTEXT(hWnd, wParam, lParam, OnSetText);<br />
		HANDLE_WM_SETFONT(hWnd, wParam, lParam, OnSetFont);<br />
<br />
		//HANDLE_WM_LBUTTONDOWN(hWnd, wParam, lParam, OnMouseButtonDown);<br />
		//HANDLE_WM_LBUTTONUP(hWnd, wParam, lParam, OnMouseButtonUp);<br />
		*/<br />
<br />
	}<br />
	<br />
	return DefWindowProc(hWnd, msg, wParam, lParam);<br />
}<br />
<br />
<br />
/***********************************************************************\<br />
FUNCTION:			OnNCCreate<br />
PURPOSE:			Intializes the control for the first time<br />
ARGS:				HWND: Handle to the button<br />
					LPCREATESTRUCT pointer<br />
RETURN:				TRUE if succuss FALSE otherwise.<br />
\***********************************************************************/<br />
BOOL OnNCCreate(HWND hWnd, LPCREATESTRUCT lpCreateStruct)<br />
{<br />
	PBUTTONINFO pButtonInfo = AllocateButtonInfoFor(hWnd);<br />
	<br />
	if(!pButtonInfo)<br />
		return FALSE;<br />
<br />
	int iLen = lstrlen(lpCreateStruct->lpszName);<br />
<br />
	if(iLen > pButtonInfo->nTextLength)<br />
	{<br />
		if(pButtonInfo->szText != NULL)<br />
			free((void *)pButtonInfo->szText);<br />
		pButtonInfo->szText = (TCHAR *) malloc(iLen + 2);<br />
		//pButtonInfo->szText = new TCHAR[iLen + 1];<br />
		<br />
		if(pButtonInfo->szText == NULL)<br />
			return FALSE;<br />
	}<br />
<br />
	pButtonInfo->nTextLength = iLen;<br />
	ZeroMemory((LPVOID)pButtonInfo->szText, pButtonInfo->nTextLength);<br />
	lstrcpy(pButtonInfo->szText, lpCreateStruct->lpszName);<br />
<br />
	<br />
<br />
	return TRUE;<br />
}<br />
<br />
/***********************************************************************\<br />
FUNCTION:			OnNCDestroy<br />
PURPOSE:			De-allocates the BUTTONINFO struct<br />
ARGS:				HWND: Handle to the button<br />
RETURN:				None<br />
\***********************************************************************/<br />
<br />
void OnNCDestroy(HWND hWnd)<br />
{<br />
	DeleteButtonInfo(hWnd);<br />
}<br />
<br />
/***********************************************************************\<br />
FUNCTION:			OnPaint<br />
PURPOSE:			Paints the control<br />
ARGS:				HWND: Handle to the button<br />
RETURN:				None<br />
\***********************************************************************/<br />
<br />
void OnPaint(HWND hWnd)<br />
{<br />
	PAINTSTRUCT ps;<br />
<br />
	PBUTTONINFO pButtonInfo = PickButtonInfo(hWnd);<br />
	HDC hdc = BeginPaint(hWnd, &ps);<br />
	<br />
	//pButtonInfo->state = (BUTTONSTATE)2;<br />
	DrawButton(hWnd, pButtonInfo, hdc);<br />
	EndPaint(hWnd, &ps);<br />
<br />
	//DropButtonInfo(hWnd);<br />
	<br />
}<br />
<br />
<br />
/***********************************************************************\<br />
FUNCTION:			OnMouseButtonDown<br />
PURPOSE:			Changes the button state<br />
ARGS:				HWND: Handle to the button<br />
RETURN:				None<br />
\***********************************************************************/<br />
<br />
void OnMouseButtonDown(HWND hWnd, int x, int y)<br />
{<br />
	PBUTTONINFO pButtonInfo = PickButtonInfo(hWnd);<br />
<br />
	if(!pButtonInfo)<br />
		return;<br />
<br />
	pButtonInfo->state = PRESSED;<br />
<br />
	InvalidateRect(hWnd, NULL, TRUE);<br />
}<br />
<br />
/***********************************************************************\<br />
FUNCTION:			OnMouseButtonUp<br />
PURPOSE:			Changes the state of the button<br />
ARGS:				HWND: Handle to the button<br />
RETURN:				None<br />
\***********************************************************************/<br />
<br />
void OnMouseButtonUp(HWND hWnd, int x, int y)<br />
{<br />
	PBUTTONINFO pButtonInfo = PickButtonInfo(hWnd);<br />
<br />
	if(!pButtonInfo)<br />
		return;<br />
<br />
	pButtonInfo->state = NORMAL;<br />
	InvalidateRect(hWnd, NULL, TRUE);<br />
	<br />
	HWND hParent = GetParent(hWnd);<br />
<br />
	if(!hParent)<br />
		return;<br />
<br />
	UINT nID = GetWindowLong(hWnd, GWL_ID);<br />
<br />
	SendMessage(hParent, WM_COMMAND, MAKEWPARAM(nID, BN_CLICKED), (LONG)hWnd);<br />
}<br />
<br />
/***********************************************************************\<br />
FUNCTION:			OnGetText<br />
PURPOSE:			Gets the text of the control<br />
ARGS:				HWND: Handle to the button<br />
RETURN:				None<br />
\***********************************************************************/<br />
<br />
INT OnGetText(HWND hWnd, int nMaxLen, LPTSTR lpszBuffer)<br />
{<br />
	PBUTTONINFO pButtonInfo = PickButtonInfo(hWnd);<br />
<br />
	if(!pButtonInfo)<br />
		return -1;<br />
<br />
	<br />
	int i = 0;<br />
<br />
//	while(i < nMaxLen && i < pButtonInfo->nTextLength)<br />
//		lpszBuffer[i] = pButtonInfo->szText[i++];<br />
<br />
	lstrcpy(lpszBuffer, pButtonInfo->szText);<br />
//	lpszBuffer[i] = '\0';<br />
<br />
	return i;<br />
}<br />
<br />
/***********************************************************************\<br />
FUNCTION:			OnGetTextLength<br />
PURPOSE:			Gets the length of text of the control<br />
ARGS:				HWND: Handle to the button<br />
RETURN:				None<br />
\***********************************************************************/<br />
<br />
INT OnGetTextLength(HWND hWnd)<br />
{<br />
	PBUTTONINFO pButtonInfo = PickButtonInfo(hWnd);<br />
<br />
	if(!pButtonInfo)<br />
		return -1;<br />
<br />
	return pButtonInfo->nTextLength;<br />
}<br />
<br />
/***********************************************************************\<br />
FUNCTION:			OnSetText<br />
PURPOSE:			Sets the of text of the control<br />
ARGS:				HWND: Handle to the button<br />
RETURN:				None<br />
\***********************************************************************/<br />
<br />
BOOL OnSetText(HWND hWnd, LPCTSTR lpszText)<br />
{<br />
	PBUTTONINFO pButtonInfo = PickButtonInfo(hWnd);<br />
<br />
	int iLen = lstrlen(lpszText);<br />
<br />
	if(iLen > pButtonInfo->nTextLength)<br />
	{<br />
		if(pButtonInfo->szText != NULL)<br />
			free((void *)pButtonInfo->szText);<br />
<br />
		pButtonInfo->szText = (TCHAR *) malloc(iLen + 2);<br />
<br />
		//pButtonInfo->szText = new TCHAR[iLen + 1];<br />
<br />
		if(pButtonInfo->szText == NULL)<br />
			return FALSE;<br />
	}<br />
<br />
	pButtonInfo->nTextLength = iLen;<br />
	ZeroMemory((LPVOID)pButtonInfo->szText, pButtonInfo->nTextLength);<br />
	lstrcpy(pButtonInfo->szText, lpszText);<br />
	<br />
	InvalidateRect(hWnd, NULL, TRUE);<br />
	return TRUE;<br />
<br />
}

Polite Programmer

More Object Oriented then C#

Re: Heap corruption.

Polite Programmer3-Jun-07 20:01

Polite Programmer

3-Jun-07 20:01

Ooooooopsssss!
Sorry for that much long message....

Polite Programmer

More Object Oriented then C#

Re: Heap corruption.

Stephen Hewitt3-Jun-07 20:05

Stephen Hewitt

3-Jun-07 20:05

Follow the steps I gave and odds are the dubugger will take you straight to the source of the problem.

Steve

help with fstream

anbluemoon3-Jun-07 1:24

anbluemoon

3-Jun-07 1:24

can anybody tell me how to read hex number in IDX file (foxpro) by using fstream::read ?

Re: help with fstream

CPallini3-Jun-07 4:02

CPallini

3-Jun-07 4:02

What do you really need to do (hex number is a bit generic, maybe, for instance, a byte, a 16-bit number... Please note: hex is only a number representation base)?

Maybe you need to:

(1) open the stream in binary mode.
(2) use the method read( unsigned char* puch, int nCount ) to get the relevant bytes.

Smile | :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

DLL and EXE files

prithaa3-Jun-07 0:43

prithaa

3-Jun-07 0:43

Hello,

I have a set of classes in .h and .cpp files.How can I make dll files and .exe files from them

Prithaa

Re: DLL and EXE files

Christian Graus3-Jun-07 1:14

Christian Graus

3-Jun-07 1:14

Where did they come from ? Did you write them ? You need to create dll and exe projects and then put your code into them.

Christian Graus - Microsoft MVP - C++
Metal Musings - Rex and my new metal blog
"I am working on a project that will convert a FORTRAN code to corresponding C++ code.I am not aware of FORTRAN syntax" ( spotted in the C++/CLI forum )

Re: DLL and EXE files

Rajesh R Subramanian3-Jun-07 20:43

Rajesh R Subramanian

3-Jun-07 20:43

Christian Graus wrote:
Where did they come from ?

Nobody can give you wiser advice than yourself. - Cicero

Re: DLL and EXE files

Matthew Faithfull3-Jun-07 1:18

Matthew Faithfull

3-Jun-07 1:18

Are you looking for a compiler? Or wanting to know how to change your build settings to get an EXE as opposed to a DLL? Unsure | :~

Nothing is exactly what it seems but everything with seems can be unpicked.

Re: DLL and EXE files

prithaa3-Jun-07 1:42

prithaa

3-Jun-07 1:42

Hello,
Yes I have made classes through VC++ MFC AppWizard(exe)option in non Doc-View architecture.
Now I want these classes to be used in my another project without actually disturbing the classes.For this purpose if I can make the .dlls and load them in my project directory and #include these .h in my project I think that will be fine.
For now what I do is Add those files in my project through the workspace area and I can actually see all the files in my workspace which I don't want.

Can do like that or I have missed something while making the classes?
Thanks for your replies
Pritaa

Re: DLL and EXE files

Matthew Faithfull3-Jun-07 2:59

Matthew Faithfull

3-Jun-07 2:59

If you've made the classes through the exe AppWizard then it isn't going to be straight forward to try and package them in a Dll. I would suggest starting a new project, An empty Dll that supports/(is linked to) MFC. Then copy the classes you want into it starting with the simplest ones. Then you need to look into exporting the classes from the dll that you want to use. Check this page for a start.
http://msdn2.microsoft.com/en-us/library/3y1sfaz2(VS.71).aspx[^]
I would recommend experimenting a little with creating simple Dlls and using them from simple EXEs before bringing MFC into the picture. Because MFC tries to be a framework it has to assume a 'model' ie EXE or DLL when is generates application classes and the code you get is targetted at one or the other. Things like individual Dialog classes are easy enough to move into a Dll but the main Doc/View classes won't be. Good luck with it anyway Smile | :)

Nothing is exactly what it seems but everything with seems can be unpicked.

Re: DLL and EXE files

Hamid_RT3-Jun-07 7:33

Hamid_RT

3-Jun-07 7:33

Do you need to Creating and consuming MFC DLLs for Beginners[^]

WhiteSky

How do I make a child dialog draw on a different HDC

KellyR2-Jun-07 17:51

KellyR

2-Jun-07 17:51

Hi,

So here's my problem:

I have a child dialog on my main window. I use double-buffering in my application and I'd like the dialog to draw on my back-buffered HDC instead of my front HDC (the HDC of the main window) to prevent flicker when it invalidates.

How can I change the HDC that the child window draws to?

Thanks!

Re: How do I make a child dialog draw on a different HDC

Naveen3-Jun-07 16:17

Naveen

3-Jun-07 16:17

KellyR wrote:
How can I change the HDC that the child window draws to?

Try specifiing the CS_OWNDC style to the child dialog.( using the SetClassLong() function )

nave

[OpenedFileFinder]

again for InterlockedIncrement()

includeh102-Jun-07 16:52

includeh10

2-Jun-07 16:52

long iv=0;
function InterlockedIncrement(&iv) is used for locking iv according its name, but variable iv is not locked after the function call.

could u explain in which case the iv is locked by the function call?

Re: again for InterlockedIncrement()

Matthew Faithfull3-Jun-07 1:07

Matthew Faithfull

3-Jun-07 1:07

iy = InterlockedIncrement(&iv); is essentially the same thing as

<br />
SomeCriticalSection.Lock();<br />
iy = (++iv);<br />
SomeCriticalSection.Unlock();<br />

The reason you would use InterlockedIncrement is if iv is being accessed by more than one thread, as you know, and you want to increment and get the value of iv with no possibility of another thread steping in and changing it in the mean time. Consider one possible break down of the unprotected code

iy = iv++;

in 'optimised' pseudo assembler Big Grin | :-D

1 load iv into a register
2 If iv is an even number
3 set bit 1 on the register
4 else
5 do a full ADD operation on 1 and iv
6 store the register contents back again into the memory of iv
//..one critical weak point is here
7 load iv from memory again
8 store it a second time into the memory of iy

In theory at least another thread could jump in at the critical weak point in the lines above, and do any amount of stuff with iv in memory D'Oh! | :doh:

Total disaster can then ensue. In practice this is unlikely because a decent compiler backend will optimise out the storing and reloading of iv before assignment to iy. It will just store the same value twice.
The reason you would still use the InterlockedIncrement is not to protect this thread but to protect the other thread which while we are stopped on step 5 writes iv (does it's own step 6) and then finds that it hasn't been written because we jump back in and write over it in our step 6. The iv and iy in the other thread will then be out of sync. Smile | :)

I have found very few situations where InterlockedIncrement is really needed but there are a few.

Nothing is exactly what it seems but everything with seems can be unpicked.

Re: again for InterlockedIncrement()

Mark Salsbery4-Jun-07 5:40

Mark Salsbery

4-Jun-07 5:40

I explained this to the OP in another post.

While you're correct about locking (probably) not needed on a simple increment,
InterlockedIncrement does more:

SomeCriticalSection.Lock();
iy = (++iv);
returnval = iv;
SomeCriticalSection.Unlock();
return returnval;

Aother thread incrementing iv after the first thread increments it but before the first thread
has copied it could have an undesired effect Smile | :)

Especially on reference counters, which is (probably) most often the reason InterlockedIncrement
and InterlockedDecrement are used.

Mark

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

Re: again for InterlockedIncrement()

Mark Salsbery4-Jun-07 5:45

Mark Salsbery

4-Jun-07 5:45

The variable is locked DURING the call, not after the call completes.

See here[^].

As Matthew mentioned, what's going on in the call is something like:

LONG InterlockedIncrement(LONG volatile* lpAddend)
{
   SomeCriticalSection.Lock();
   ++(*lpAddend);
   LONG returnval = *lpAddend;
   SomeCriticalSection.Unlock();
   return returnval;
}

Mark

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

Suggestion: Subject Matter Editors

Jeffrey Walton2-Jun-07 11:46

Jeffrey Walton

2-Jun-07 11:46

Hi All,

I know this has come up in the context of non-English speaking contributors in an effort to improve article quality. I'm all for it. I submit that the non-English speaking author has a better command of English than I have of his native tongue. So I am humbled by my own ignorance...

However, Subject Matter is a different story. I have a good understanding in some arenas. This knowledge extends sufficiently so that I feel I can provide feedbck and advice. One such area is Cryptography.

I am appaled at some of the articles submitted on Cryptography. In the following, I am not singling out the authors. I am trying to make a succint point.

The latest is TrueCrypt Explorer[^]. This library is using source code and presumably home grown ciphers from the notorius Tom St. Dennis of sci.crypt. Single handedly, he nearly ruined the usenet group with his arrogance and ignorance.

I assume the author is not versed on Cryptography, and as such has fallen victim to TSD's 'Proof by Intimidation' of his cryptosystem. I am not aware of a Cryptanalytic effort by any reputable cryptographer on his work.

Build your own cryptographically safe server/client protocol[^] is misleading because the author states something to the nature he is collecting 'true randomness', which is generally not possible in software.

CTrueRandom - Getting True Random Numbers[^] claims it generates 'True Random Numbers'. I assume the author meant nondeterminsitic method, similar to the noise resisitor placed on the hardware based PRNG board of a RS6000.

As a final example, I point you toward The Art & Science of Storing Passwords[^], where the article claims the practice of storing a password for recover on disk unencrypted is OK.

Jeff

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