Memory Leak Queries! - C / C++ / MFC Discussion Boards

Re: string, basic_string, stl and UNICODE

Michael P Butler5-Nov-01 3:42

5-Nov-01 3:42

So I have to do my only #ifdef UNICODE and define mystring as string or wstring?

Is there any difference between the c_str method and the data method of string?

Thanks for you answers,

Michael Smile | :)

Re: string, basic_string, stl and UNICODE

Tomasz Sowinski5-Nov-01 3:58

Tomasz Sowinski

5-Nov-01 3:58

So I have to do my only #ifdef UNICODE and define mystring as string or wstring?

Yes. Or you can go fancy and use TCHAR:

typedef basic_string<TCHAR, char_traits<TCHAR>, allocator<TCHAR> > mystring;

Is there any difference between the c_str method and the data method of string?

Yes - data() doesn't guarantee that you'll get the terminating null character. If the string is empty, data returns "a non-null pointer that cannot be dereferenced" according to docs that shipped with VC6

Tomasz Sowinski -- http://www.shooltz.com

Printing specific area of the dialog form?

Deian5-Nov-01 0:16

Deian

5-Nov-01 0:16

Hello, I've no clue on how to print a specific area of the form on my SDI App. The view class is dialog based. The reason I need to do this is because it has to look the same on the document as on the form - the form has 46 static controls with text and 46 edit boxes - so I have no clue how to print them exactly as they are placed

Any help appreciated,

Deian

Change something on the other dialog?

Rickard Andersson²⁰4-Nov-01 23:34

Rickard Andersson²⁰

4-Nov-01 23:34

Hi!
In my main dialog (the dialog that appears when I run my app) I have a button that opens a second dialog (the dialog box have a WS_POPUP style), in the main dialog I want to start a timer + change the text of some controls (statics etc.)
Now to the problem: I have code to do that when I close the dialog. But I want to start a timer and change some stuff immediate when I push a button on the second dialog!! HOW!??

/*
BETA
*/

Re: Change something on the other dialog?

Tomasz Sowinski5-Nov-01 0:44

Tomasz Sowinski

5-Nov-01 0:44

But I want to start a timer and change some stuff immediate when I push a button on the second

You push on a second dialog and want to change something on a second dialog? Or push on a second and want to change on first?

Tomasz Sowinski -- http://www.shooltz.com

Re: Change something on the other dialog?

6-Nov-01 1:34

are these modaless dialogs u r talkin bout???

Database exception

Jimmy Ehrnström4-Nov-01 23:09

Jimmy Ehrnström

4-Nov-01 23:09

In my program I'm calling a stored procedure (SQL Server) several times. Most of the times it works fine, but eventually I get the following exception:

"Could not allocate a new object descriptor for required system catalog in database '6'. Another database must be closed or objects in another database dropped in order to open this database."

Here's the code that generates the exception:

prsStolpe->MoveFirst();
CString sql;
sql.Format("{CALL TabortBesiktning(%d, %d)}", 
prsStolpe->m_LinjeomradeId, prsStolpe->m_StolpeId);
prsStolpe->m_pDatabase->ExecuteSQL(sql);
prsStolpe->Edit();
Initiera();
prsStolpe->Update();

I suspect that the combination of recordset and ExecuteSQL might cause the exception, but then I don't understand why it works fine for several calls before the exception occurs.

I did a search on the exception string and read something about the cause being "resource limitation". What resource would that be?

Please help me out if you can. I'm as confused as a baby in a topless bar. Confused | :confused:

Thanks!

Memory Leak Queries!

AJ1234-Nov-01 22:51

AJ123

4-Nov-01 22:51

Hi,

I have a suspicion that there is a memory leak in a ActiveX App that I am working on.

The reason for the suspicion is the containing application occassionally doesn't redraw correctly.

During this investigation i am going to ignore the activeX technology for the moment.

Anyway, i am sifting through the code to make sure that all mallocs are properly free and dynamic objects destroyed. But surely a problem with one of these wouldn't cause the current symptons.

Some one sugested that the problem might be caused by messages which are left when the app finishes? is this likely? How would i handle it? Anyone any other ideas of what to watch out for?

Thanks Again
Rich

Can we know the available memory at runtime?

Dhanush4-Nov-01 22:29

Dhanush

4-Nov-01 22:29

Can we know the available memory at runtime in other words how can we make sure that our program doesn't have any memory (even a single byre.)?
If anybody knows plz answer me.

Re: Can we know the available memory at runtime?

Nish Nishant4-Nov-01 22:40

Nish Nishant

4-Nov-01 22:40

Take a look at GlobalMemoryStatus

Nish

Sonork ID 100.9786 voidmain

Re: Can we know the available memory at runtime?

Tomasz Sowinski4-Nov-01 22:56

Tomasz Sowinski

4-Nov-01 22:56

in other words how can we make sure that our program doesn't have any memory (even a single byre.)?

Your program always uses some memory. What exactly do you want to achieve?

Tomasz Sowinski -- http://www.shooltz.com

Re: Can we know the available memory at runtime?

Dhanush10-Nov-01 1:25

Dhanush

10-Nov-01 1:25

Sorry, the question is incomplete. How can i be sure that my program( program or an activex component)doesn't have any memory leaks and how can i prove it to somebody else.
Thanx in advance.

changing the value of a recordset's property

Yair Konfino4-Nov-01 22:26

Yair Konfino

4-Nov-01 22:26

Hi,
I'm trying to change the value of a recordset's property. The property is "scroll backwards" (want to change from false to true).

I opened a recordset, and then I got it's properties. I got the wanted property(according to it's index), but I can't change the value - I get an error saying that "the operation can't be done when the object is open".

Which object is the error talking about?
Do I need to change the property after openning the recordset?
What am I doing wrong?

Can someone please send me a code example of what should I do...???

Thanks.

Color

Deian4-Nov-01 21:59

Deian

4-Nov-01 21:59

hey, i know that this will sound stupid, but i can't find any function that changes the static control's text color. Example of doing that?

Thanks,

Deian

Re: Color

Nish Nishant4-Nov-01 22:21

Nish Nishant

4-Nov-01 22:21

Put this in the OnCtlColor

if(nCtlColor==CTLCOLOR_STATIC )
{
	pDC->SetBkColor(RGB(255,9,9));
	pDC->SetTextColor(RGB(9,9,255));
}

Replace the RGB values with what you prefer

Regards
Nish

Sonork ID 100.9786 voidmain

Re: Color

Eugene Pustovoyt4-Nov-01 22:31

Eugene Pustovoyt

4-Nov-01 22:31

Such function is not present, you're must override OnCtlColor() function

HBRUSH ...OnCtlColor(...)
{
   HBRUSH hbr = CDialog::OnCtlColor(pDC, pWnd, nCtlColor);

   if (pWnd->GetDlgCtrlID() == IDC_STATIC1) //ID your control
   {
      pDC->SetBkMode(TRANSPARENT);
      pDC->SetTextColor (RGB (255, 0, 0)); //red color
   }
   return hbr;
}

Re: Color

Joaquín M López Muñoz4-Nov-01 23:08

Joaquín M López Muñoz

4-Nov-01 23:08

There's no direct way to accomplish this, and others have already pointed out the method to be used. If you want to save you the pain of writing and maintaining this kind of stuff, why not have a look at Yuri Goltsam's Colored/Blinking Controls and Dialogs with any Font article. Simple drop-in solution. I specially like the idea of providing the functionality as a template class, wish this technique was more widely known and adopted.

Joaquín M López Muñoz
Telefónica, Investigación y Desarrollo

Re: Color

5-Nov-01 0:07

thanks

Serialize problem

bashi4-Nov-01 20:09

bashi

4-Nov-01 20:09

hi there...
well im new 2 vc so bear my kiddish query
i have an SDI and have a variable of CString in CDocument...
my view class is of type CEditView and i want to save the
contents typed in the edit view in my doc CString variable and then this variable to disk using the file_save button on the toolbar...
thanx in advance

Averaging & Median Filters

4-Nov-01 19:50

Hi, can i know how to use median and averaging filter? My program now can capture real image using digital camera. But how do i reduce the noise using averaging and median filter?? I'm beginner to this and do not know what the filters are for. Please help. Thanks Alot!

Regards,
Michelle

Re: Averaging & Median Filters

markkuk4-Nov-01 20:00

markkuk

4-Nov-01 20:00

See this introduction to digital filters

Boot Disk?

Stephen Caldwell4-Nov-01 18:16

Stephen Caldwell

4-Nov-01 18:16

I was just pondering one day ....

Well anyway, how would one go about coding a boot disk, like the win98 boot disk, lilo, norton ghost, etc. What kind of code would be necessary so that the system doesn't give an Invalid System Disk Error?

Well what do you know...I ended up finding something already. Heh. Fugetaboutit!
Stephen Caldwell
Blackfission, CEO
http://bf.steffc.yi.org:81

Re: Boot Disk?

markkuk4-Nov-01 20:28

markkuk

4-Nov-01 20:28

I believe this page about the PC boot process could be helpful.

Re: Boot Disk?

Jon Hulatt4-Nov-01 22:52

Jon Hulatt

4-Nov-01 22:52

From a DOS/Win3.1/Win95/Win98 machine, do a "format a: /s"

Sorry to dissapoint you all with my lack of a witty or poignant signature.

VC++ Multi-Threaded Add-In...

4-Nov-01 18:14

Ok, I'm wanting to have VC++ go to open a file and go to a particular line in the file... the filename and line number will be sent from an *external* application.

So far, my idea was to write a VC++ add-in that opened a named pipe at waited for a message from the external app. (If someone has a better suggestion, please let me know...) Here is my problem:

In CDSAddIn::OnConnection(...), I create a new thread with AfxBeginThread(...) that makes the pipe and waits. After receiving the message, the pipe calls a new function in the CCommands class, which in turn should open the passed file and go to the line as so:

STDMETHODIMP CCommands::OpenAndGoTo(BSTR szFilename, int nLine)
{
AFX_MANAGE_STATE(AfxGetStaticModuleState());

IDocuments* pDocuments = NULL;
m_pApplication->get_Documents((IDispatch**)&pDocuments);

// open the file
ITextDocument* pDoc = NULL;
CComBSTR bstrFileName = szFilename;
CComVariant vtDocType = "Text";
CComVariant vtReadOnly = FALSE;
pDocuments->Open(bstrFileName, vtDocType, vtReadOnly, (IDispatch**)&pDoc);

// TODO: go to the line number

return S_OK;
}

Everything works fine until the call to pDocuments->Open(...), which crashes with an unhandled exception: access violation error. The really weird thing is, the exact same function works perfectly fine when called from somewhere inside the main thread (i.e. if I call the function from the CDSAddIn::OnConnection(...) function, everything works perfect). It only crashes when I call the function from the created thread. Any ideas as to why?!

Thanks for your help...
~ Stevo

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