C / C++ / MFC

Re: How can i design, To calculate's the objects in a class

14-Aug-06 1:20

U r looking for objects in a class or objects of a class? If it is the later, ie how to track the the number of objects created for a class, u can use below demo.

class InstanceCntDemo{<br />
<br />
private :<br />
	static int nCnt;	<br />
public:<br />
	InstanceCntDemo(){<br />
		nCnt++;<br />
	}<br />
	static int GetCnt()<br />
	{<br />
		return nCnt;<br />
	}<br />
};<br />
int InstanceCntDemo::nCnt =0;<br />
<br />
int main(){<br />
<br />
	InstanceCntDemo ic;<br />
	InstanceCntDemo ic1;<br />
	InstanceCntDemo ic2;<br />
	InstanceCntDemo ic3;<br />
<br />
	int nCnt = InstanceCntDemo::GetCnt(); <br />
};

Does this make sense?

Cheers MiltonKB.

premkamalg16-Aug-06 1:27

premkamalg

16-Aug-06 1:27

Thanks Mr.MiltonKB.

Hi,
Thanks, if u think it's good.
otherwise sorry.

Limiting an application to single instance...problem? [modified]

Vinod Sankaranarayanan13-Aug-06 23:16

Re: Limiting an application to single instance...problem?

13-Aug-06 23:16

Dear all,

I had one MDI application and I want to limit its execution to single instance.

I had tried source code from lots of articles (i.e Newcomer's, Naughter ...Armen...)

it will work ...but while closing the second instance it raises an exception ...

Abnormal program termination!!!

This exception generated from "WinMain" when the
"pthread->ExitInstance()" get called...

How can I solve this ?

I am using Windows XP SP2 .....and VC++ 6.0

Thanks in advance......

-- modified at 5:17 Monday 14th August, 2006

vinsankar

prasad_som13-Aug-06 23:44

prasad_som

13-Aug-06 23:44

how you are limiting its instances ?

Prasad
Notifier using ATL

Re: Limiting an application to single instance...problem?

Vinod Sankaranarayanan14-Aug-06 0:01

Re: Limiting an application to single instance...problem?

14-Aug-06 0:01

Hi,
Try these links......

1.
http://www.codeproject.com/threads/singleinstancemfc.asp

2.
http://www.codeproject.com/library/PlgInArchSingInst.asp

3.
http://www.codeproject.com/threads/singleinstance.asp

4.

http://www.codeproject.com/cpp/csingleinst.asp

vinsankar

prasad_som14-Aug-06 0:15

prasad_som

14-Aug-06 0:15

I tried first link only. But cant get second instance.
Can you explain it in detail?

Prasad
Notifier using ATL

Re: Limiting an application to single instance...problem?

Vinod Sankaranarayanan14-Aug-06 1:08

Re: Limiting an application to single instance...problem?

14-Aug-06 1:08

Hi ,

How will u get second instance?

those articles tell u abt preventing the second instance from running when there is already one instance running on ur desktop....

ok.........

vinsankar

Milton Karimbekallil14-Aug-06 1:42

Re: Limiting an application to single instance...problem?

14-Aug-06 1:42

There are no direct APIs or functions to identify which is second instance or third instance and so on.
Why do u need second instance?
What exactly is the problem u r facing?

If something is crashing in the ExistInstance in the second time, you have to find out which statement is crashing.

It may be because, u r trying to access an un initialized variable there which may get initialized in the first instance as InitInstance will execute completely in the first instance.

But in the second instance you may bypass those initializations and exits after the 'previous instance' checking. Then when control reaches ExitInstance it will crash as what ever u r accessing is not initialized. Just a thought. chk it out.

Cheers..Milton KB.

Vinod Sankaranarayanan14-Aug-06 2:34

Re: Limiting an application to single instance...problem?

14-Aug-06 2:34

Hi,

Sorry.......

I don't need the second instance......I want to prevent all other instances while one is there..

then.....

I fix it .....

I made a mistake in the "return statement" after finding the previous instance of that program in the 'InitInstance()' of my App class.

I was written like this...
BOOL CMyApp::InitInstance()
{
if(IsthereApreviousInstance(....GUID))
{
AfxMessageBox("Already one Instance");
return FALSE; // This is wrong
}

}

The above code will work but an exception will raised...

So I put it like this....

exit(0); // in place of "return FALSE"

Ok.............Thanks....to all

vinsankar

Waldermort14-Aug-06 2:10

Waldermort

14-Aug-06 2:10

When the first instance starts execution, the very first thing it should do is check for a mutex, if not found it should create one. When the second instance starts, it should check for the mutex, when it finds it it should terminate.

Look at the CreateMutex() and GetLastError() functions.

I'm not sure where to do this in MFC, but in Win32 these routines are the first to be executed in WinMain(). Also note all of this should be done before creating/reading any other variables.

I have a header file containing all these functions and a few more like handling Command line paramaters, and handling MultiUser/MultiDesktop environments. (A modified combination of CP examples). If you like I will send it to you.

Re: Limiting an application to single instance...problem...solution [modified]

Vinod Sankaranarayanan14-Aug-06 2:36

Re: Limiting an application to single instance...problem?

14-Aug-06 2:36

Hi,

I solve it ....
See my previous message....

Thanks....

-- modified at 11:31 Monday 14th August, 2006

vinsankar

prasad_som15-Aug-06 18:49

prasad_som

15-Aug-06 18:49

Vinod A Sankaranarayanan wrote:
How will u get second instance?

that's why I wanted you to explain in detail.
Anyway you solve your problem, and shared,too.Thats good.

Prasad
Notifier using ATL

How to vopy data pointed by a "Void* " pointer to "CString" object

VCSharp00713-Aug-06 23:15

VCSharp007

13-Aug-06 23:15

Hi,
I have to copy the data pointed by "void*" to a CString object.
Which is the best way?

code:

void* pVoid = 0;
CString csData;
pVoid = new BYTE(100);

// Do some thing

// ??? (Here I have to copy data from void* to CString.)
delete[] pVoid;
AfxMessageBox( csData );

Thnx in advance.

Re: How to vopy data pointed by a "Void* " pointer to "CString" object

Waldermort14-Aug-06 1:59

Waldermort

14-Aug-06 1:59

Use a typecast i.e.

csData = (char*)pVoid;

You should probably validate the data in pVoid first, not sure how CString would respond if the data wasn't NULL terminated.

Re: How to vopy data pointed by a "Void* " pointer to "CString" object

ajisthekingofpop14-Aug-06 5:45

ajisthekingofpop

14-Aug-06 5:45

void* pVoid = 0;
CString csData;
pVoid = new BYTE(100);

I would do the following:

memcpy(&csData, pVoid, 100);

//I would use a #define for the 100 tho because it make sit easier to understand

Now this has copied the data from one object to another WITHOUT using a reference.

Re: How to vopy data pointed by a "Void* " pointer to "CString" object

Joe Woodbury14-Aug-06 12:32

Joe Woodbury

14-Aug-06 12:32

DO NOT USE THE IMMEDIATE ABOVE SUGGESTION; it will result in a buffer overrun and is VERY poor coding practice.

Two general methods:

1) Cast the void pointer to a char, tchar or wchar_t pointer.

2) Call CString::GetBuffer() with the length of buffer you require. Copy the data in and then call CString::ReleaseBuffer().

You will want to to the latter if your buffer contains multiple zero terminated strings since method one will terminate the copy at the first null.

Anyone who thinks he has a better idea of what's good for people than people do is a swine.
- P.J. O'Rourke

Multicolumn CListCtrl & custom DrawItem

Martijn van Kleef13-Aug-06 22:30

Martijn van Kleef

13-Aug-06 22:30

Hi,

Can anyone please help me implement a custom (override) DrawItem method for a multicolumn CListCtrl, in particular for the individual columns / subitems? Here's what I have so far:

<br />
void CColoredListCtrl::DrawItem(LPDRAWITEMSTRUCT lpDrawItemStruct)<br />
{<br />
	CString							csItemText = GetItemText(lpDrawItemStruct->itemID, 0);<br />
	CDC							dc;<br />
<br />
	dc.Attach(lpDrawItemStruct->hDC);<br />
<br />
	// Save these value to restore them when done drawing<br />
	COLORREF						crOldTextColor = dc.GetTextColor();<br />
	COLORREF						crOldBkColor = dc.GetBkColor();<br />
<br />
	if (lpDrawItemStruct->itemData != NULL)<br />
		dc.SetTextColor((COLORREF)lpDrawItemStruct->itemData);<br />
<br />
	if ((lpDrawItemStruct->itemAction | ODA_SELECT) && (lpDrawItemStruct->itemState & ODS_SELECTED))<br />
	{<br />
		dc.SetBkColor(::GetSysColor(COLOR_HIGHLIGHT));<br />
		dc.FillSolidRect(&lpDrawItemStruct->rcItem, ::GetSysColor(COLOR_HIGHLIGHT));<br />
	}<br />
	else<br />
	{<br />
		if ((lpDrawItemStruct->itemID % 2) == 1)<br />
			dc.FillSolidRect(&lpDrawItemStruct->rcItem, ::GetSysColor(COLOR_BTNFACE));<br />
		else<br />
			dc.FillSolidRect(&lpDrawItemStruct->rcItem, ::GetSysColor(COLOR_WINDOW));<br />
	}<br />
<br />
	// Draw the text<br />
	dc.DrawText(csItemText.GetBuffer(), csItemText.GetLength(), &lpDrawItemStruct->rcItem, DT_LEFT | DT_SINGLELINE | DT_VCENTER);<br />
<br />
	// Reset the background color and the text color back to their original values<br />
	dc.SetTextColor(crOldTextColor);<br />
	dc.SetBkColor(crOldBkColor);<br />
<br />
	dc.Detach();<br />
}<br />

I'm having trouble with the very first line in this method. It always gets the itemtext of the first column, but I'm having a multicolumn listctrl so I also need to know which subitem to get. This method is called from calls to CListCtrl::InsertItem and CListCtrl::SetItemText which get called in a multithreaded context. I was hoping the LPDRAWITEMSTRUCT would have subitem info but it doesn't seem to.

Also, does the lpDrawItemStruct->itemData member contain the info that was set by calls to CListCtrl::SetItemData??

Re: Multicolumn CListCtrl & custom DrawItem

Milton Karimbekallil13-Aug-06 23:52

Re: Multicolumn CListCtrl & custom DrawItem

13-Aug-06 23:52

Use the GetColumn(), GetSubItemRect() and GetItemRect() methods to navigate to the subitems. See this sample for more details http://www.codeproject.com/listctrl/SubItemSel.asp[^]

cheers..Milton KB

Hamid_RT14-Aug-06 1:18

Hamid_RT

14-Aug-06 1:18

See XListCtrl - A custom-draw list control with subitem formatting[^]maybe it is some helpful to you

WhiteSky

Access to other computer. How to?

thangnvhl13-Aug-06 21:22

13-Aug-06 21:22

Dear,
I am trying to write a program that can access to other computer in my LAN with a specified user name and password. Please show me how to do this. I am working with C API.
Thank you very much.

Sincerely
Thangnvhl

Milton Karimbekallil13-Aug-06 22:55

13-Aug-06 22:55

Hope what u need is to access the file system on the remote computer.
For this u have to impersonate the user context of ur application to a user who has acceess on the remote machine.

So by using the username and password u have, call LogonUser API.
Then call ImpersonateLoggedOnUser by passing the tocken u received as out from LogonUser.

Once impersonataed, eitehr u can use the unc path to access the remote file system, or if it not shared u can use the default NT share c$, d$ etc for each drive.

cheers Milton KB

thangnvhl14-Aug-06 0:27

14-Aug-06 0:27

It's really worked.
Thank you so much

Sincerely
Thangnvhl

thangnvhl15-Aug-06 22:46

15-Aug-06 22:46

I am verry sorry. I try to create one program and it really worked at only my computer with current user. I could not connect to other computers, even my localhost with other accounts. LogonUser always returned FALSE. Please could you give me some code. Needn't API, non MFCs are OK.

Sincerely
Thangnvhl

thangnvhl15-Aug-06 22:46