Re: value duplication issue - C / C++ / MFC Discussion Boards

Neville Franks24-Sep-04 12:29

24-Sep-04 12:29

The are a number of compact DBM's around if you don't want to write one yourself. eg. SQLite is very popular.

Neville Franks, Author of ED for Windows www.getsoft.com and coming soon: Surfulater www.surfulater.com

Re: How to go about this...

cmk24-Sep-04 13:35

cmk

24-Sep-04 13:35

Just use the dbf format.
The format description is available all over the net as well as source to read/write the files.

...cmk

Save the whales - collect the whole set

Re: How to go about this...

mirano24-Sep-04 23:58

mirano

24-Sep-04 23:58

okay guys, thank you very much for your help in this. I will now go to examine some of your thoughts in more details.

Bye.

.

value duplication issue

Paul Swet24-Sep-04 8:39

Paul Swet

24-Sep-04 8:39

The issue is:
You are given an array of integers of size n containing values in the range 1 to n-1. Obviously there’s at least one duplicate value in this array. Please let me know the algorithm for finding one such duplicate value.

Thanks.

Re: value duplication issue

David Crow24-Sep-04 8:54

David Crow

24-Sep-04 8:54

Hint: sort the array.

"When I was born I was so surprised that I didn't talk for a year and a half." - Gracie Allen

Re: value duplication issue

Arsalan Malik24-Sep-04 18:57

Arsalan Malik

24-Sep-04 18:57

Why is it obvious that there's atleast one duplicate value in this array? Smile | :)

ARSALAN MALIK

Re: value duplication issue

Paul Swet24-Sep-04 21:41

Paul Swet

24-Sep-04 21:41

Since that the array size is n and the values are from 1 to n-1

Re: value duplication issue

cmk24-Sep-04 22:28

cmk

24-Sep-04 22:28

If the array is sorted then use a binary search to check the value at each position against the value of the position :
if ( a[i] == i+1 ) then the duplicate is in the section greater than i
else the duplicate is in the section less than or equal to i.

If the array isn't sorted then allocate a temp array of size n and walk through the original putting 'check marks' in the temp array at the appropriate index (value-1). As soon as you find a value that has alreay been 'checked' you have your duplicate.

...cmk

Save the whales - collect the whole set

Visual C++ 2005 Beta

Anonymous24-Sep-04 6:50

Anonymous

24-Sep-04 6:50

Can anyone tell me if the Application Wizard that exists in Visual Studio 6 is no longer availabe in the new version of Visual Studio? I am so used to working with that wizard and it was such a dissapointment for me not to find it in Visual C++ 2005.

Re: Visual C++ 2005 Beta

Alexander ^M.,24-Sep-04 12:24

Alexander ^M.,

24-Sep-04 12:24

Visual C++ .NET 2005 has it's own appliation wizard.

Don't try it, just do it! Wink | ;-)

Re: Visual C++ 2005 Beta

Gary R. Wheeler24-Sep-04 16:15

Gary R. Wheeler

24-Sep-04 16:15

In VS.NET 2002 and 2003, it's part of the File|New|Project operation. I would imagine it's in the same place in 2005.

Software Zen: delete this;

Re: Visual C++ 2005 Beta

Anonymous26-Sep-04 9:37

Anonymous

26-Sep-04 9:37

Well, it's not there, that's what puzzled me. I still cannot find it. I gave up already.

How to read image files with extensions which are not predefined in C#

Kiran Satish24-Sep-04 6:16

Kiran Satish

24-Sep-04 6:16

Hi all,

I am having some image files with extensions which are not predefined in GDI+ Image library of C#.
I have tried various other libraries, but none of them are having the capability of reading my image files. My image files are in *.LL1 and *.LT1 formats.

If anyone know, how to read any fle of unknown format in C#, Plz lemme know and I truely appreciate any kind of help.

thanks in advance,

Pavan

ActiveX C++ Button ctrl

Andy H24-Sep-04 5:49

Andy H

24-Sep-04 5:49

I have written an ActiveX control based on the BUTTON. The only problem I am having at present is when the mouse hovers over the button it doesn't paint the control image in the HOT state. Could some kind person explain where I have gone wrong.

My .CPP file is below:

<br />
// CmdButtonCtl.cpp : Implementation of the CCmdButtonCtrl ActiveX Control class.<br />
<br />
#include "stdafx.h"<br />
#include "CmdButton.h"<br />
#include "CmdButtonCtl.h"<br />
#include "CmdButtonPpg.h"<br />
<br />
<br />
#ifdef _DEBUG<br />
#define new DEBUG_NEW<br />
#undef THIS_FILE<br />
static char THIS_FILE[] = __FILE__;<br />
#endif<br />
<br />
<br />
IMPLEMENT_DYNCREATE(CCmdButtonCtrl, COleControl)<br />
<br />
<br />
/////////////////////////////////////////////////////////////////////////////<br />
// Message map<br />
<br />
BEGIN_MESSAGE_MAP(CCmdButtonCtrl, COleControl)<br />
	//{{AFX_MSG_MAP(CCmdButtonCtrl)<br />
	ON_WM_CREATE()<br />
	ON_WM_MOUSEMOVE()<br />
	ON_WM_LBUTTONDOWN()<br />
	ON_WM_LBUTTONUP()<br />
	//}}AFX_MSG_MAP<br />
	ON_MESSAGE(OCM_COMMAND, OnOcmCommand)<br />
	ON_MESSAGE(OCM_DRAWITEM, OnOcmDrawItem)<br />
	ON_MESSAGE(WM_MOUSELEAVE, OnMouseLeave)<br />
	ON_OLEVERB(AFX_IDS_VERB_PROPERTIES, OnProperties)<br />
END_MESSAGE_MAP()<br />
<br />
<br />
/////////////////////////////////////////////////////////////////////////////<br />
// Dispatch map<br />
<br />
BEGIN_DISPATCH_MAP(CCmdButtonCtrl, COleControl)<br />
	//{{AFX_DISPATCH_MAP(CCmdButtonCtrl)<br />
	DISP_PROPERTY_NOTIFY(CCmdButtonCtrl, "Caption", m_szCaption, OnCaptionChanged, VT_BSTR)<br />
	DISP_STOCKPROP_FONT()<br />
	//}}AFX_DISPATCH_MAP<br />
END_DISPATCH_MAP()<br />
<br />
<br />
/////////////////////////////////////////////////////////////////////////////<br />
// Event map<br />
<br />
BEGIN_EVENT_MAP(CCmdButtonCtrl, COleControl)<br />
	//{{AFX_EVENT_MAP(CCmdButtonCtrl)<br />
	// NOTE - ClassWizard will add and remove event map entries<br />
	//    DO NOT EDIT what you see in these blocks of generated code !<br />
	//}}AFX_EVENT_MAP<br />
END_EVENT_MAP()<br />
<br />
<br />
/////////////////////////////////////////////////////////////////////////////<br />
// Property pages<br />
<br />
// TODO: Add more property pages as needed.  Remember to increase the count!<br />
BEGIN_PROPPAGEIDS(CCmdButtonCtrl, 1)<br />
	PROPPAGEID(CCmdButtonPropPage::guid)<br />
	PROPPAGEID(CLSID_CFontPropPage)<br />
END_PROPPAGEIDS(CCmdButtonCtrl)<br />
<br />
<br />
/////////////////////////////////////////////////////////////////////////////<br />
// Initialize class factory and guid<br />
<br />
IMPLEMENT_OLECREATE_EX(CCmdButtonCtrl, "CMDBUTTON.CmdButtonCtrl.1",<br />
	0xe1b9af4b, 0x701e, 0x4d9d, 0x94, 0xf0, 0x36, 0x43, 0x1f, 0x70, 0x3c, 0xee)<br />
<br />
<br />
/////////////////////////////////////////////////////////////////////////////<br />
// Type library ID and version<br />
<br />
IMPLEMENT_OLETYPELIB(CCmdButtonCtrl, _tlid, _wVerMajor, _wVerMinor)<br />
<br />
<br />
/////////////////////////////////////////////////////////////////////////////<br />
// Interface IDs<br />
<br />
const IID BASED_CODE IID_DCmdButton =<br />
		{ 0xb0c488ad, 0x8522, 0x4fbf, { 0xa3, 0xa5, 0xa8, 0x1c, 0x4d, 0x9f, 0x6a, 0x3a } };<br />
const IID BASED_CODE IID_DCmdButtonEvents =<br />
		{ 0x4bbc4b44, 0xa6ae, 0x49e3, { 0x8d, 0xaf, 0x91, 0x2e, 0x6e, 0x48, 0xee, 0x9e } };<br />
<br />
<br />
/////////////////////////////////////////////////////////////////////////////<br />
// Control type information<br />
<br />
static const DWORD BASED_CODE _dwCmdButtonOleMisc =<br />
	OLEMISC_ACTIVATEWHENVISIBLE |<br />
	OLEMISC_SETCLIENTSITEFIRST |<br />
	OLEMISC_INSIDEOUT |<br />
	OLEMISC_CANTLINKINSIDE |<br />
	OLEMISC_RECOMPOSEONRESIZE;<br />
<br />
IMPLEMENT_OLECTLTYPE(CCmdButtonCtrl, IDS_CMDBUTTON, _dwCmdButtonOleMisc)<br />
<br />
<br />
/////////////////////////////////////////////////////////////////////////////<br />
// CCmdButtonCtrl::CCmdButtonCtrlFactory::UpdateRegistry -<br />
// Adds or removes system registry entries for CCmdButtonCtrl<br />
<br />
BOOL CCmdButtonCtrl::CCmdButtonCtrlFactory::UpdateRegistry(BOOL bRegister)<br />
{<br />
	// TODO: Verify that your control follows apartment-model threading rules.<br />
	// Refer to MFC TechNote 64 for more information.<br />
	// If your control does not conform to the apartment-model rules, then<br />
	// you must modify the code below, changing the 6th parameter from<br />
	// afxRegApartmentThreading to 0.<br />
<br />
	if (bRegister)<br />
		return AfxOleRegisterControlClass(<br />
			AfxGetInstanceHandle(),<br />
			m_clsid,<br />
			m_lpszProgID,<br />
			IDS_CMDBUTTON,<br />
			IDB_CMDBUTTON,<br />
			afxRegApartmentThreading,<br />
			_dwCmdButtonOleMisc,<br />
			_tlid,<br />
			_wVerMajor,<br />
			_wVerMinor);<br />
	else<br />
		return AfxOleUnregisterClass(m_clsid, m_lpszProgID);<br />
}<br />
<br />
<br />
/////////////////////////////////////////////////////////////////////////////<br />
// CCmdButtonCtrl::CCmdButtonCtrl - Constructor<br />
<br />
CCmdButtonCtrl::CCmdButtonCtrl()<br />
{<br />
	InitializeIIDs(&IID_DCmdButton, &IID_DCmdButtonEvents);<br />
<br />
	// TODO: Initialize your control's instance data here.<br />
	m_bMouseOverButton = false;<br />
	m_bLMouseButtonDown = false;<br />
}<br />
<br />
<br />
/////////////////////////////////////////////////////////////////////////////<br />
// CCmdButtonCtrl::~CCmdButtonCtrl - Destructor<br />
<br />
CCmdButtonCtrl::~CCmdButtonCtrl()<br />
{<br />
	// TODO: Cleanup your control's instance data here.<br />
}<br />
<br />
<br />
/////////////////////////////////////////////////////////////////////////////<br />
// CCmdButtonCtrl::OnDraw - Drawing function<br />
<br />
void CCmdButtonCtrl::OnDraw(<br />
			CDC* pdc, const CRect& rcBounds, const CRect& rcInvalid)<br />
{<br />
	DoSuperclassPaint(pdc, rcBounds);<br />
}<br />
<br />
<br />
/////////////////////////////////////////////////////////////////////////////<br />
// CCmdButtonCtrl::DoPropExchange - Persistence support<br />
<br />
void CCmdButtonCtrl::DoPropExchange(CPropExchange* pPX)<br />
{<br />
	ExchangeVersion(pPX, MAKELONG(_wVerMinor, _wVerMajor));<br />
	COleControl::DoPropExchange(pPX);<br />
<br />
	// TODO: Call PX_ functions for each persistent custom property.<br />
	PX_String( pPX, _T("Caption"), m_szCaption, _T("Caption"));<br />
}<br />
<br />
<br />
/////////////////////////////////////////////////////////////////////////////<br />
// CCmdButtonCtrl::OnResetState - Reset control to default state<br />
<br />
void CCmdButtonCtrl::OnResetState()<br />
{<br />
	COleControl::OnResetState();  // Resets defaults found in DoPropExchange<br />
<br />
	// TODO: Reset any other control state here.<br />
}<br />
<br />
<br />
/////////////////////////////////////////////////////////////////////////////<br />
// CCmdButtonCtrl::PreCreateWindow - Modify parameters for CreateWindowEx<br />
<br />
BOOL CCmdButtonCtrl::PreCreateWindow(CREATESTRUCT& cs)<br />
{<br />
	cs.lpszClass = _T("BUTTON");<br />
	return COleControl::PreCreateWindow(cs);<br />
}<br />
<br />
<br />
/////////////////////////////////////////////////////////////////////////////<br />
// CCmdButtonCtrl::IsSubclassedControl - This is a subclassed control<br />
<br />
BOOL CCmdButtonCtrl::IsSubclassedControl()<br />
{<br />
	return TRUE;<br />
}<br />
<br />
<br />
/////////////////////////////////////////////////////////////////////////////<br />
// CCmdButtonCtrl::OnOcmCommand - Handle command messages<br />
<br />
LRESULT CCmdButtonCtrl::OnOcmCommand(WPARAM wParam, LPARAM lParam)<br />
{<br />
#ifdef _WIN32<br />
	WORD wNotifyCode = HIWORD(wParam);<br />
#else<br />
	WORD wNotifyCode = HIWORD(lParam);<br />
#endif<br />
<br />
	// TODO: Switch on wNotifyCode here.<br />
	switch(wNotifyCode)<br />
	{<br />
		case BN_CLICKED:<br />
			FireClick();<br />
			break;<br />
		case BN_KILLFOCUS:<br />
<br />
			break;<br />
	}<br />
<br />
	return 0;<br />
}<br />
<br />
LRESULT CCmdButtonCtrl::OnOcmDrawItem(WPARAM wParam, LPARAM lParam)<br />
{<br />
	UINT nIDCtl = (UINT) wParam;<br />
	LPDRAWITEMSTRUCT lpDrawItemStruct = (LPDRAWITEMSTRUCT) lParam;<br />
	HDC dc = lpDrawItemStruct->hDC;<br />
	CDC* pDC = CDC::FromHandle(dc);<br />
<br />
	// Button state:<br />
	BOOL bIsSelected = (lpDrawItemStruct->itemState & ODS_SELECTED);<br />
	BOOL bIsFocussed = (lpDrawItemStruct->itemState & ODS_FOCUS);<br />
	BOOL bIsDisabled = (lpDrawItemStruct->itemState & ODS_DISABLED);<br />
<br />
	CRect rect;<br />
	rect.CopyRect(&lpDrawItemStruct->rcItem);<br />
	<br />
	#ifdef _VISUALSTYLE_XP_H_<br />
	if( g_xpStyle.IsAppThemed() )<br />
	{<br />
		HTHEME hTheme = g_xpStyle.OpenThemeData(GetSafeHwnd(), L"BUTTON");<br />
		int state = 1;<br />
<br />
		if(bIsSelected)<br />
			state = 2;<br />
		if(m_bLMouseButtonDown)<br />
			state = 3;<br />
<br />
		CRect rcContent = rect;<br />
		InflateRect(&rcContent, -3, -3);<br />
<br />
		HRESULT hr = g_xpStyle.DrawThemeBackground(hTheme, dc, 1, state , &rect, NULL);<br />
		hr = g_xpStyle.GetThemeBackgroundContentRect(hTheme, dc, 1, state, &rect, &rcContent);<br />
		<br />
		// Draw caption text:<br />
		if(!m_szCaption.IsEmpty())<br />
		{<br />
			LPWSTR lpszCaption = new WCHAR[m_szCaption.GetLength()];<br />
			LPSTR lpStr = m_szCaption.GetBuffer(m_szCaption.GetLength());<br />
			int nLen = MultiByteToWideChar(CP_ACP, 0, lpStr, -1, NULL, NULL);<br />
			MultiByteToWideChar(CP_ACP, 0, lpStr, -1, lpszCaption, nLen);<br />
<br />
			CFont* pOldFont = SelectStockFont(pDC);<br />
			hr = g_xpStyle.DrawThemeText(hTheme, dc, 1, state, lpszCaption, wcslen(lpszCaption), <br />
											DT_CENTER | DT_VCENTER | DT_SINGLELINE,<br />
											0, &rect);<br />
			pDC->SelectObject(pOldFont);<br />
			hr = g_xpStyle.CloseThemeData(hTheme);<br />
		}<br />
	}<br />
	else<br />
	{<br />
	#endif<br />
		// Draw without XP themeing:<br />
		CBrush brBackground;<br />
		brBackground.CreateSolidBrush(GetSysColor(COLOR_BTNFACE));<br />
<br />
		if(bIsFocussed)<br />
		{<br />
			HBRUSH br = CreateSolidBrush(RGB(0, 0 ,0));<br />
			FrameRect(dc, &rect, br);<br />
			InflateRect(&rect, -1, -1);<br />
			DeleteObject(br);<br />
		}<br />
<br />
		FillRect(dc, &rect ,brBackground);<br />
<br />
		if(bIsSelected)<br />
		{<br />
			HBRUSH br = CreateSolidBrush(GetSysColor(COLOR_BTNSHADOW));<br />
			FrameRect(dc, &rect, br);<br />
			DeleteObject(br);<br />
		}<br />
		else<br />
		{<br />
			UINT uState = DFCS_BUTTONPUSH | ((m_bMouseOverButton) ? 0x1000 : 0) | <br />
				((bIsSelected) ? DFCS_PUSHED : 0);<br />
			DrawFrameControl(dc, &rect, DFC_BUTTON, uState);<br />
		}<br />
		<br />
		if(!m_szCaption.IsEmpty())<br />
		{<br />
			CFont* pOldFont = SelectStockFont(pDC);<br />
			int iOldMode = pDC->GetBkMode();<br />
			COLORREF crOldText = pDC->GetTextColor();<br />
<br />
			CRect rcContent = rect;<br />
			InflateRect(&rcContent, -3, -3);<br />
			CSize Extent = pDC->GetTextExtent(m_szCaption);<br />
			CPoint pt(rcContent.CenterPoint().x - Extent.cx/2, rcContent.CenterPoint().y - Extent.cy/2);<br />
					<br />
			pDC->SetBkMode(TRANSPARENT);<br />
			pDC->SetTextColor(GetSysColor(COLOR_BTNTEXT));<br />
			<br />
			if(bIsDisabled)<br />
			{<br />
				CBrush brGray;<br />
				brGray.CreateSolidBrush(GetSysColor(COLOR_GRAYTEXT));<br />
				pDC->GrayString(&brGray, NULL, (LPARAM)((LPCSTR)m_szCaption), -1, rcContent.left, rcContent.top, rcContent.Width(), rcContent.Height());<br />
			}<br />
			else<br />
			{<br />
				pDC->DrawText(m_szCaption, rcContent, DT_CENTER | DT_VCENTER | DT_SINGLELINE);<br />
			}<br />
<br />
			// Draw focus rect.<br />
			if(bIsFocussed)<br />
			{<br />
				DrawFocusRect(dc, &rcContent);<br />
			}<br />
<br />
			pDC->SetBkMode(iOldMode);<br />
			pDC->SetTextColor(crOldText);<br />
		}<br />
	#ifdef _VISUALSTYLE_XP_H_<br />
	}<br />
	#endif<br />
<br />
	return 0;<br />
}<br />
<br />
/////////////////////////////////////////////////////////////////////////////<br />
// CCmdButtonCtrl message handlers<br />
<br />
void CCmdButtonCtrl::PreSubclassWindow() <br />
{	<br />
	COleControl::PreSubclassWindow();<br />
	ModifyStyle(0, BS_OWNERDRAW|BS_NOTIFY);<br />
}<br />
<br />
int CCmdButtonCtrl::OnCreate(LPCREATESTRUCT lpCreateStruct) <br />
{<br />
	if (COleControl::OnCreate(lpCreateStruct) == -1)<br />
		return -1;<br />
	<br />
	// TODO: Add your specialized creation code here<br />
	<br />
	return 0;<br />
}<br />
<br />
void CCmdButtonCtrl::OnMouseMove(UINT nFlags, CPoint point) <br />
{<br />
	COleControl::OnMouseMove(nFlags, point);<br />
<br />
	if(!m_bMouseOverButton)<br />
	{<br />
		TRACKMOUSEEVENT t = {sizeof(TRACKMOUSEEVENT), TME_LEAVE, m_hWnd, 0};<br />
		if(::_TrackMouseEvent(&t))<br />
		{<br />
			m_bMouseOverButton = true;<br />
			Invalidate();<br />
		}<br />
	}<br />
}<br />
<br />
LRESULT CCmdButtonCtrl::OnMouseLeave(WPARAM, LPARAM)<br />
{<br />
	ASSERT(m_bMouseOverButton);<br />
	m_bMouseOverButton = false;<br />
	Invalidate();<br />
	return 0;<br />
}<br />
<br />
void CCmdButtonCtrl::OnCaptionChanged() <br />
{<br />
	// TODO: Add notification handler code<br />
<br />
	SetModifiedFlag();<br />
}<br />
<br />
void CCmdButtonCtrl::OnLButtonDown(UINT nFlags, CPoint point) <br />
{<br />
	COleControl::OnLButtonDown(nFlags, point);<br />
	if(m_bMouseOverButton)<br />
	{<br />
		m_bLMouseButtonDown = true;<br />
		Invalidate();<br />
	}<br />
}<br />
<br />
void CCmdButtonCtrl::OnLButtonUp(UINT nFlags, CPoint point) <br />
{<br />
	COleControl::OnLButtonUp(nFlags, point);<br />
	if(m_bMouseOverButton)<br />
	{<br />
		m_bLMouseButtonDown = false;<br />
		Invalidate();<br />
	}<br />
}<br />

RAS fucntions problem

Muhammad Asif Khan24-Sep-04 4:57

Muhammad Asif Khan

24-Sep-04 4:57

Hello every body
I am using RasEnumConnections fucntion to check if i am alreay connected to internent or not. I have installed Plateform SDK installed on my system having Windows XP OS. It works fine. But when I port this code on a Win2k machine, even in the form of binary or I recompile(build) the code on that system having PSDK installed as well, the function gives error as ERROR_INVALID_SIZE (632) from RASERROR.H i.e invalid structure size. I have used the sample lines of code given in MSDN. The function is using RASCON structure which differes on the basis of operating system. When I unregister PSDK directories on my Win2k machine the fucntion starts working. In this case it gets structure size as 412 instead of 704 bytes as were assigned in case of PSDK directories registered or on WindowsXP machine. Can some one tell me some solution. I need PSDK directories registered with VC as I need some PSDK function in my application. I have tried /D_WINNT_WIN32=500 compiler option as given in MSDN in the help page of WINVER, but it didn't worked.

Thanx in advance
Waiting 4 ur responce

Re: RAS fucntions problem

vcplusplus24-Sep-04 9:01

vcplusplus

24-Sep-04 9:01

Try using InternetGetConnectedState(...) instead.
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/wininet/wininet/internetgetconnectedstate.asp?frame=true[^]

Re: RAS fucntions problem

Alexander ^M.,24-Sep-04 12:26

Alexander ^M.,

24-Sep-04 12:26

This is the best way because enumerating RAS connections won't show you an internet connection in any case. Just imagine you have a hardware router and you use your network card for the internet connection. This is not RAS, so your detection routine will fail.

Don't try it, just do it! Wink | ;-)

Re: RAS fucntions problem

Muhammad Asif Khan26-Sep-04 21:54

Muhammad Asif Khan

26-Sep-04 21:54

First thanx 4 ur reply, but the problem is that I am going to connect internet always using DUN(DialUp Networking). Infact what in my software, i need to check is whether i am connected to internet or not ( I have to check it only for DUN). If I am connected, ok, other wise I have to show the user possible DUN connections dialog, then on user selection, open the dialup dialog for selected connections and on succsessfull connectivity to internet, I have to start monitoring the internet connections, so as the internet get disconnected, i let the user know abt it. I am using RasEventNotification method for that. Now what do u suggest 4 that. Is there any alternative 4 that.

Re: RAS fucntions problem

Ken Andrews27-Sep-04 7:15

Ken Andrews

27-Sep-04 7:15

The problem is that the RASENTRY size changes from 98/Me to 2K and then again in XP. What I have done is to define different structs for each of these sizes and in my code switch to the correct struct based on the OS that I am running on.

would someone tell me if this is OK?

BlackDice24-Sep-04 3:33

BlackDice

24-Sep-04 3:33

I posted a couple of questions yesterday about a BYTE array created on the heap. After creating it I use SafeArrayAccessData() and SafeArrayUnAccessData() after puttin the info in the array. This is the exact same method I've seen used in countless examples when I googled this stuff. However, I was getting a memory leak because I didn't call 'delete' on the pointer. When I tried to call delete on the pointer, my program ASSERTed in _CrtIsValidHeapPointer(). I never wrote to the array after that and can't figure out why it's doing that, so here's what I did:

UINT nAddress = 0;
BYTE* pBuf = NULL;

//some other stuff

pBuf = new BYTE[nLength];
nAddress = (UINT)pBuf;  //to hold initial address.

//continue with code, and catch handler

if(nAddress)
{
    pBuf = (BYTE*)nAddress;
    delete [] pBuf;
    pBuf = NULL;
}

It's been working so far, and not MEMORY LEAKS, but...
Is this okay?

[insert witty comment here]

bdiamond Sleepy | :zzz:

Re: would someone tell me if this is OK?

Antony M Kancidrowski24-Sep-04 3:58

Antony M Kancidrowski

24-Sep-04 3:58

I would tend to ensure that the pBuf pointer is never moved from the start of the array and always delete it.

BYTE* pBuf = NULL;
pBuf = new BYTE[nLength];

BYTE* pTemp = pBuf;
// Do something using pTemp rather than pBuf

delete [] pBuf;
pBuf = NULL;

Hope I have not misunderstood your intensions.

Ant.

I'm hard, yet soft.
I'm coloured, yet clear.
I'm fruity and sweet.
I'm jelly, what am I? Muse on it further, I shall return! - David Williams (Little Britain)

Re: would someone tell me if this is OK?

BlackDice24-Sep-04 4:12

BlackDice

24-Sep-04 4:12

actually, it's already doing that in the code I omitted. There's another variable called pBytes that I use, but I was still getting that ASSERT.

[insert witty comment here]

bdiamond Sleepy | :zzz:

Re: would someone tell me if this is OK?

Antony M Kancidrowski24-Sep-04 4:37

Antony M Kancidrowski

24-Sep-04 4:37

Um strange. If pBuf doesn't become corrupted then you should not have an ASSERT.

I would tend to alter the code back to how you had it and step through with the debugger watching the value of pBuf.

I guess you are masking a bigger problem here!

Ant.

I'm hard, yet soft.
I'm coloured, yet clear.
I'm fruity and sweet.
I'm jelly, what am I? Muse on it further, I shall return! - David Williams (Little Britain)

Re: would someone tell me if this is OK?

David Crow24-Sep-04 4:42

David Crow

24-Sep-04 4:42

Antony M Kancidrowski wrote:
I guess you are masking a bigger problem here!

Agreed.

"When I was born I was so surprised that I didn't talk for a year and a half." - Gracie Allen

Re: would someone tell me if this is OK?

BlackDice24-Sep-04 4:57

BlackDice

24-Sep-04 4:57

Okay I put the code back how it was (good thing I'm using SourceSafe). When stepping through the code, this is what happened. After stepping through the line where the pointer is allocated (see line 1) the value in the watch window is
0x01970190 "ÍÍÍÍÍÍÍÍÍÍÍ" unsigned char *
after stepping through line 2 the value is:
0x0018f760 "ÐÏà¡±á" unsigned char *

here are the lines:

Line 1: pBuf = new BYTE[nLength];
Line 2: SafeArrayAccessData(varBLOB.parray,(void **)&pBuf);

Also, I see the type is listed as 'unsigned char*' in both, and pBuf is declared like this:

BYTE* pBuf;

[insert witty comment here]

bdiamond Sleepy | :zzz:

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