C / C++ / MFC

14-Dec-08 1:40

Hello everyone,

For SetWaitableTimer and CreateWaitableTimer, I have the confusions (even after

Google, I can not find satisfied answers, seems the samples are very few and MSDN

description is fuzzy).

My questions are,

1. For API SetWaitableTimer, what are the meaning and function of parameters

pDueTime and lPeriod?

http://msdn.microsoft.com/en-us/library/ms686289.aspx

2. For API CreateWaitableTimer, what is the function and meaning of parameter

bManualReset (what is the different between setting it to true and setting it to false)?

http://msdn.microsoft.com/en-us/library/ms682492.aspx

thanks in advance,
George

Stuart Dootson14-Dec-08 6:25

14-Dec-08 6:25

Look at this page[^]:
- pDueTime is a pointer to a FILETIME that indicates how long (from now) until the timer expires.
- lPeriod shows the timer's period, i.e. the time between timer expirations
If *pDueTime was set to 10 milliseconds and lPeriod to 5 ms, the timer would fire 10, 15, 02, 25... milliseconds from now.
If a timer has bManualReset set to TRUE, then you have to call SetWaitableTimer to make it start measuring time again after it expires. If a timer has bManualReset set to FALSE, then it becomes active again once a WaitForSingleObject or WaitForMultipleObjects call has been activated by the timer expiry.

George_George14-Dec-08 20:14

14-Dec-08 20:14

Thanks Stuart,

I would like to write simple samples until I understand the concept. Smile | :)

Stuart Dootson wrote:
If a timer has bManualReset set to TRUE, then you have to call SetWaitableTimer to make it start measuring time again after it expires.

You mean for example, I set the lPeriod to 5 ms, and then active the timer, then the timer only activate after 5ms once? Not active after 5ms, 10ms, 15ms, etc?

2.

Stuart Dootson wrote:
a timer has bManualReset set to FALSE, then it becomes active again once a WaitForSingleObject or WaitForMultipleObjects call has been activated by the timer expiry.

I am confused about what do you mean, could you show some pseudo code or refer some samples? I did not find any good samples from MSDN.

regards,
George

Stuart Dootson14-Dec-08 21:19

14-Dec-08 21:19

George_George wrote:
You mean for example, I set the lPeriod to 5 ms, and then active the timer, then the timer only activate after 5ms once? Not active after 5ms, 10ms, 15ms, etc

I don't think bManualReset has any effect when you have a non-zero period. Not sure, though. As I said, try it and see!

George_George wrote:

Stuart Dootson wrote:
a timer has bManualReset set to FALSE, then it becomes active again once a WaitForSingleObject or WaitForMultipleObjects call has been activated by the timer expiry.

I am confused about what do you mean, could you show some pseudo code or refer some samples? I did not find any good samples from MSDN.

How about this?[^]

George_George15-Dec-08 0:42

15-Dec-08 0:42

Hi Stuart,

I think when non-zero period is used, bManualReset is also useful. Here is my code to show my ideas. Any comments?

#define _WIN32_WINNT 0x0500

#include <windows.h>
#include <stdio.h>

int main()
{
    HANDLE hTimer = NULL;
    LARGE_INTEGER liDueTime;

    liDueTime.QuadPart=-100000000LL;

    // Create a waitable timer.
    hTimer = CreateWaitableTimer(NULL, TRUE, "WaitableTimer");
    if (NULL == hTimer)
    {
        printf("CreateWaitableTimer failed (%d)\n", GetLastError());
        return 1;
    }

    printf("Waiting for 10 seconds...\n");

	while(1)
	{
		// Set a timer to wait for 10 seconds.
		if (!SetWaitableTimer(hTimer, &liDueTime, 5000, NULL, NULL, 0))
		{
			printf("SetWaitableTimer failed (%d)\n", GetLastError());
			return 2;
		}

		// Wait for the timer.

		if (WaitForSingleObject(hTimer, INFINITE) != WAIT_OBJECT_0)
			printf("WaitForSingleObject failed (%d)\n", GetLastError());
		else printf("Timer was signaled.\n");
	}

    return 0;
}

regards,
George

Jijo.Raj14-Dec-08 6:37

Jijo.Raj

14-Dec-08 6:37

George_George wrote:
1. For API SetWaitableTimer, what are the meaning and function of parameters

pDueTime and lPeriod?

http://msdn.microsoft.com/en-us/library/ms686289.aspx

pDueTime - means exactly at which point of time, the timer should trigger first. If the value is positive, then it will be considered as absolute time else considered as relative time. Well, from your question it seems you're confused with absolute and relative time? isn't it? I'll explain a bit.

Absolute time - Assume you want to trigger the timer on New Year! In that case your timer should trigger on 1-Jan-2009 0:01 AM. So you can convert that time into a FILETIME value by using the function SystemTimeToFileTime()[^]and specify it as pDueTime and your timer will be signed exactly at that point.

Relative time - Just think about snoozing your outlook reminder for 10 minutes. That means - from NOW to 10 minutes. So you can specify the 10 minutes duration with negative sign. So the timer will be triggered exactly after 10 minutes.

As it says one is absolute - which means you exactly know the point of time and another is relative - means the value you specify is the duration of time from NOW, when the timer is to be signaled.

lPeriod - Assume after setting the timer at Midnight newyear, you want it to signal again in interval of 5 minutes - to wake up from bed Wink | ;)

. In that case set this parameter as 5 minutes in milliseconds. Literally, it means the duration for trigger the same timer in periodic fashon, After it signalled for the first time. If you specify this param, then after first signalling, it will signal periodically by the specified time duration.

Phewww!!! I admit that it was a bit long. Hope it will be helpful to you.

Regards,
Jijo.

_____________________________________________________

http://weseetips.com[^] Visual C++ tips and tricks. Updated daily.

George_George14-Dec-08 20:20

Query XML in SQL 2005 using ADO in native C++

14-Dec-08 20:20

Thanks Jijo!

Excellent reply! Smile | :)

How about your ideas for my question #2 below?

2. For API CreateWaitableTimer, what is the function and meaning of parameter

bManualReset (what is the different between setting it to true and setting it to false)?

http://msdn.microsoft.com/en-us/library/ms682492.aspx

regards,
George

Green Fuze13-Dec-08 12:42

Green Fuze

13-Dec-08 12:42

Hey everybody!

Does anyone know how can I query a view using ADO (and SQLOLEDB) and get back XML?

In other words, how can I perform something like:
"Select * from students FOR XML AUTO" in ADO???

I cannot find any way to tell ADO to return as XML (I do not want to use text, but use ADO objects).

Thanks a lot in advance!

[Message Deleted]

chokahn13-Dec-08 3:50

chokahn

13-Dec-08 3:50

[Message Deleted]

Re: reading bitmap pixel by pixel??

Jijo.Raj13-Dec-08 3:56

Jijo.Raj

13-Dec-08 3:56

You could use CBitmap::LoadBitmap()[^] to load the bitmap from file. Then, call CBitmap::GetBitmapBits()[^] to get the bitmap data, so that you can access it pixel by pixel.

Regards,
Jijo.

_____________________________________________________

http://weseetips.com[^] Visual C++ tips and tricks. Updated daily.

Re: [Message Deleted]

Jijo.Raj13-Dec-08 4:57

Jijo.Raj

13-Dec-08 4:57

When i prepared the reply your second question, you have deleted your post. OMG | :OMG:

What happend? Well, anyway i'm posting the prepared reply.

If you find trouble in using CBitmap, then i'll recommend you SDK functions to do the same. Well, you can use LoadImage()[^] to load the bitmap and you'll get a handle. Then by using GetBitmapBits()[^] you could access the bitmap data. Well check this article[^] about how to load the image by using LoadImage().

Regards,
Jijo.

_____________________________________________________

http://weseetips.com[^] Visual C++ tips and tricks. Updated daily.

Creating DialogBar in VC 2008

sabapathy_8013-Dec-08 3:13

sabapathy_80

13-Dec-08 3:13

I have tried creating DialogBar in MDI application using VC 2008 with steps mentioned in Dialog Bars[^]. But when running application only document is there but not the Dialogbar.

The code generated by MFC in CMainFrame::OnCreate() is different from the sample as follows:

<br />
	if (CMDIFrameWndEx::OnCreate(lpCreateStruct) == -1)<br />
		return -1;<br />
<br />
	BOOL bNameValid;<br />
<br />
	CMDITabInfo mdiTabParams;<br />
	mdiTabParams.m_style = CMFCTabCtrl::STYLE_3D_ONENOTE; // other styles available...<br />
	mdiTabParams.m_bActiveTabCloseButton = TRUE;      // set to FALSE to place close button at right of tab area<br />
	mdiTabParams.m_bTabIcons = FALSE;    // set to TRUE to enable document icons on MDI taba<br />
	mdiTabParams.m_bAutoColor = TRUE;    // set to FALSE to disable auto-coloring of MDI tabs<br />
	mdiTabParams.m_bDocumentMenu = TRUE; // enable the document menu at the right edge of the tab area<br />
	EnableMDITabbedGroups(TRUE, mdiTabParams);<br />
<br />
	if (!m_wndMenuBar.Create(this))<br />
	{<br />
		TRACE0("Failed to create menubar\n");<br />
		return -1;      // fail to create<br />
	}<br />
<br />
	m_wndMenuBar.SetPaneStyle(m_wndMenuBar.GetPaneStyle() | CBRS_SIZE_DYNAMIC | CBRS_TOOLTIPS | CBRS_FLYBY);<br />
<br />
	// prevent the menu bar from taking the focus on activation<br />
	CMFCPopupMenu::SetForceMenuFocus(FALSE);<br />
<br />
	if (!m_wndToolBar.CreateEx(this, TBSTYLE_FLAT, WS_CHILD | WS_VISIBLE | CBRS_TOP | CBRS_GRIPPER | CBRS_TOOLTIPS | CBRS_FLYBY | CBRS_SIZE_DYNAMIC) ||<br />
		!m_wndToolBar.LoadToolBar(theApp.m_bHiColorIcons ? IDR_MAINFRAME_256 : IDR_MAINFRAME))<br />
	{<br />
		TRACE0("Failed to create toolbar\n");<br />
		return -1;      // fail to create<br />
	}<br />
<br />
	CString strToolBarName;<br />
	bNameValid = strToolBarName.LoadString(IDS_TOOLBAR_STANDARD);<br />
	ASSERT(bNameValid);<br />
	m_wndToolBar.SetWindowText(strToolBarName);<br />
<br />
	CString strCustomize;<br />
	bNameValid = strCustomize.LoadString(IDS_TOOLBAR_CUSTOMIZE);<br />
	ASSERT(bNameValid);<br />
	m_wndToolBar.EnableCustomizeButton(TRUE, ID_VIEW_CUSTOMIZE, strCustomize);<br />
<br />
<br />
if( !m_wndToolbox.Create(this,<br />
		          IDD_TOOLBOX,<br />
		   CBRS_LEFT | CBRS_GRIPPER | CBRS_TOOLTIPS | CBRS_FLYBY,<br />
		          IDD_TOOLBOX) )<br />
{<br />
	TRACE0(_T("Failed to create the toolbox\n"));<br />
	return -1;<br />
}<br />
// When the dialog bar is undocked, display a caption on its title bar<br />
m_wndToolbox.SetWindowText("Toolbox");<br />
<br />
<br />
<br />
	if (!m_wndStatusBar.Create(this))<br />
	{<br />
		TRACE0("Failed to create status bar\n");<br />
		return -1;      // fail to create<br />
	}<br />
	m_wndStatusBar.SetIndicators(indicators, sizeof(indicators)/sizeof(UINT));<br />
<br />
	// TODO: Delete these five lines if you don't want the toolbar and menubar to be dockable<br />
	m_wndMenuBar.EnableDocking(CBRS_ALIGN_ANY);<br />
	m_wndToolBar.EnableDocking(CBRS_ALIGN_ANY);<br />
<br />
m_wndToolbox.EnableDocking(CBRS_ALIGN_LEFT | CBRS_ALIGN_RIGHT);<br />
<br />
	EnableDocking(CBRS_ALIGN_ANY);<br />
	DockPane(&m_wndMenuBar);<br />
	DockPane(&m_wndToolBar);<br />
<br />
<br />
	// enable Visual Studio 2005 style docking window behavior<br />
	CDockingManager::SetDockingMode(DT_SMART);<br />
	// enable Visual Studio 2005 style docking window auto-hide behavior<br />
	EnableAutoHidePanes(CBRS_ALIGN_ANY);<br />
<br />
	// Enable enhanced windows management dialog<br />
	EnableWindowsDialog(ID_WINDOW_MANAGER, IDS_WINDOWS_MANAGER, TRUE);<br />
<br />
	// Enable toolbar and docking window menu replacement<br />
	EnablePaneMenu(TRUE, ID_VIEW_CUSTOMIZE, strCustomize, ID_VIEW_TOOLBAR);<br />
<br />
	// enable quick (Alt+drag) toolbar customization<br />
	CMFCToolBar::EnableQuickCustomization();<br />
<br />
	return 0;<br />

Hamming error check and correct

King Tran13-Dec-08 2:40

King Tran

13-Dec-08 2:40

I have 20M data to transfer through the net without one bit error,so i have to use the Hamming code to check and correct the data.
anyone can provide the implementation of Hamming code with C/C++,suppose the transfer input data is : unsigned char* buff=new char[1024*1024*20];

thanks. Smile | :)

Re: Hamming error check and correct

Stuart Dootson13-Dec-08 9:24

Re: Hamming error check and correct

13-Dec-08 9:24

If only there was some way of searching the Internet[^] - then, you might have found this this[^], which seems to be a Hamming code implementation in C...

Richard Andrew x6413-Dec-08 10:33

Richard Andrew x64

13-Dec-08 10:33

Sure is a shame that there's no way to search for such stuff...

Question regarding Visual C++ redistributable

Zerox MXI13-Dec-08 2:26

Zerox MXI

13-Dec-08 2:26

Does the latest Visual C++ redistributable, 2008 SP1, contain cumulative binaries of earlier C++ binaries, for instance 2003 and 2005 ones?

Or each redistributable package is a standalone installation?

Regards.

Re: Question regarding Visual C++ redistributable

Stuart Dootson13-Dec-08 9:31