Re: memory leaks - C / C++ / MFC Discussion Boards

* the easiest way to analyze memory leaks would be to use numegas bound's checker (http://www.microway.com.au/compuware/products.stm)but this is a product you have to buy.. but it should be very good and it reports both memory and resource leaks..

* there is the mfc way to detect memory leaks.. if you are very lucky you can double click on your memory leaks and then the devstudio shows you the code, where the memory got allocated (works sometimes for me.. but i actually dunno when, maybe the objects have to be derived from cobject or whatever)
another way (happened in one of my coworker's programs) the program crashed when the program got closed (it was an invalid timer - handle he wanted to delete) and the result was that noone of the destructors ever got called.. (it is pretty simple to check that case.. if you are using cstring.. and the dump tells you that there occured memory leaks in strcore.h then this is most likely)

if you want to know if one of your methods is leaking memory you can use the CMemoryState Class...

i hope one of your ideas can help you..
bernhard

excuse my bad english, i'm austrian...

""Politicians and diapers have one thing in common. They should both be changed regularly and for the same reason."

I've used BoundsChecker a few times over the past several years and it's helped me very little. Often times it's just plain annoying in the amount of "who cares" stuff it reports. Other times it's just too slow to wait for. Still, a lot of people seem to like it, especially for finding GDI resource leaks, so...

The MFC way is pretty reliable for memory leaks. All you need is this at the top of every CPP file, after the includes:

#ifdef _DEBUG
#define new DEBUG_NEW
#undef THIS_FILE
static char THIS_FILE[] = __FILE__;
#endif

... and you'll get the name of the source files in the memory dump at the end of the program. Then you can double click on the file and you'll see who's allocating memory that doesn't get freed. Concentrate on fixing the ones in your own code, of course.

Regards,
Alvaro

Oh, and please excuse my bad English, I'm American Smile | :)

If you find that the dumped memory leaks can't be located by double-clicking, you can also try a method described in MSDN. The article is called:

HOWTO: Use _crtBreakAlloc to Debug a Memory Allocation

Basically, you use the numbers shown next to the memory leak dumps, set a variable in the debugger, and the program will break when the leaking memory is allocated. Handy.

------------------------
Derek Waters
derek@lj-oz.com

i have to admit that i never used BoundsChecker.. cause.. i haven't felt a real urge to use it.. the mfc way worked pretty well for me all the time.. (the thingie you wrote with the double click.. i never found that out..)
but now my question: is there a handy way to find resource leaks in a mfc program ?
(seems to be an advantage of using boundschecker..)

have a good one

bernhard

oh.. and yaya.. you know the game..

""Politicians and diapers have one thing in common. They should both be changed regularly and for the same reason."

thank you a lot for your ideas.. I found out a leak thanks to you, but there are some others I can't find bexause the title of the file is not complete. I can't see why... probably a bug with the debugger...lol

have you tried derek water's tip above.. maybe this could help you..

bernhard

""Politicians and diapers have one thing in common. They should both be changed regularly and for the same reason."

Resource leaks? What are those? Smile | :)

For those I'm pretty sure you need a tool like BoundsChecker or Purify.

If you use MFC, the CGdiObject-derived and CDC-derived classes, like CFont, CPaintDC, CPen, and CBrush clean themselves up via their destructors. This reduces your chances of having resource leaks. Still, if I had a GDI intensive app, I'd consider getting a tool to ensure it cleaned itself up properly.

Regards,
Alvaro

Though I go along with the others, specially the likes of bounds checker, I tend to build in a bit of quicky debugging. Afteral, you get told you have memory leaks so all you need to know is 'can my code exit without passing the cleanup' and 'does my clean up clean them all'.

Typically a node creation/deletion will follow the same few paths. If none of your memory is freed then that will be pretty obvious to fix, if only some are not freed then it is likely to be a program path problem

So, I count them in and count them out in the debug. Then print the debug value.

For example, lets say I have something like this below that is part of a xml scema parser. I have global counters,

#ifdef TRACE_TREE_MEMLEAKS
long m_Count_Tree_Leaks;
#endif

const int IN_SCHEMA_TREE = 1;
const int IN_XML_TREE = 0;
void SchemaTree::StoreSingleLineRootItem(LPCTSTR Line, int WhichTree)
#ifdef TRACE_TREE_MEMLEAKS
//include at every insert point. I had 5 ways into my two trees.
++m_Count_Tree_Leaks;
#endif
ElementTypeTree* ETType = new ElementTypeTree;
CString sLine, lSearchFor;

//fill item details

if(WhichTree == IN_SCHEMA_TREE)
m_DataTree.InsertDataItem(ETType,NULL);
else
m_XMLTree.InsertDataItem(ETType,NULL);
}

The multiline element type can create none or many subelements, so I would have these counted in too.

void SchemaTree::StoreMultiLineRootItem(int TreeLevel, LPCTSTR ItemString)
{
static CString RootItemName;
ElementTypeTree* ETType;
SubElements* subType;
CString sLine, lString, lSearchFor;
#ifdef TRACE_TREE_MEMLEAKS
//include at every insert point. I had 5 ways into my two trees.
++m_Count_Tree_Leaks;
++m_Count_Tree_Sub_Leaks;
#endif
ETType = new ...
subType = new ...

Then use
#ifdef TRACE_TREE_MEMLEAKS
--m_Count_Tree_Leaks;
--m_Count_Tree_Sub_Leaks;
#endif
at each point there are deleted.

I put this sort of stuff in from the beginning, it easy then, your not likely to miss one.

printing the debug counters values before exit (each possible exit) will tell you you have memory leaks, and which of your structures in is doing it.

We do it for the joy of seeing the users struggle.

This query is related to using an ActiveX control in VC++(Volo view Express of
AutoDesk AutoCad,free download availabe at
http://www3.autodesk.com. This is an ActiveX control
to view drawing files).
I used Volo View to view a drawing file on different computers.The volo view
always displays the same part of the drawing irrespective of the resolution of the
computers.

I have created a Dialog based application in VC++ and
inserted the Volo view Express into it(Through the Insert ActiveX control command).
As usual a wrapper class is created and inserted into project along with various
helper functions.I've also mapped the File Open menu to allow the user to select a drawing file.
If I now open the same drawing file which I had tested on different computers,the
drawing displayed is not similar to the one shown by volo view.The VC++ application displays
part of the drawing not shown by Volo. I want to know why the
drawing file is displayed differently when it is viewed through Volo view embedded in VC++
application.More over the VC++ application displays different parts of the drawing on different
computers.
How can I make the VC++ application to always display the same part of drawing irrespective
of the application running on different computers.
Any inputs in this regard would be of great help..

Thanks Ravi

Confused | :confused:

Are the resolutions of the displays different. And do you size your drawing taking this into account.

10 pixels on 800x600 is bigger than on 1024x{whatsit}

We do it for the joy of seeing the users struggle.

Hi all,
How can i add Hot spot to my .HLP ?
Please write simple example ...
Thanks ...

My month article: Game programming by DirectX by Lan Mader.
Please visit in: www.geocities.com/hadi_rezaie/index.html

Hadi Rezaie

Help files are built from .RTF files. In the RTF file, you can create a link (or hot spot) from one topic to another using this syntax:

{\uldb Hot spot topic text}{\v HID_OF_TOPIC_TO_SHOW}

Various flags can be used as follows:

\uldb - jumps to this topic from the current topic
\ul - Link to a pop-up topic

Roger Allen
Sonork 100.10016

Hi Allen !

Can i use of it in my .HLP file ?
Because my help file is in .HLP mode (Context help)
and my help not .CHM mode !
So, can i use of it in .HLP ?

My month article: Game programming by DirectX by Lan Mader.
Please visit in: www.geocities.com/hadi_rezaie/index.html

Hadi Rezaie

Your applications .hlp file is compiled when your project is compiled (if any of the files have changed). If you look in the Hlp sub directory of your project, you should see some .rtf files call AfxPrint.rtf and AfxCore.rtf. These are the default help topic for a typical application. You need to edit one of these. I normaly do this in the VC editor, but when I open the file, I change the Open as option in the file open dialog to Text so it doesn't hide all the .rtf format strings.

If you open one of these files, you can add a new topic with a hot spot to a different topic in it. You will then need to re-compiler yout .hlp file and make sure its in the same directory as your applications .exe file.

You can compile the .hlp file manually yourself, by using the tool MS V6->MS VC tools->Help workshop You should then browse to your projects .hpj file in the Hlp directory. You can then access the options to compile the .hlp file when you do changes to the .rtf files. Once compiled copy the generated .hlp file to the release/debug directory and test it with your application.

Roger Allen
Sonork 100.10016

Thanks for your helps Wink | ;)

Best Regards,

My month article: Game programming by DirectX by Lan Mader.
Please visit in: www.geocities.com/hadi_rezaie/index.html

Hadi Rezaie

Hi all,
How can i show Help Context icon in my dialog title bar ?

Please help me !

My month article: Game programming by DirectX by Lan Mader.
Please visit in: www.geocities.com/hadi_rezaie/index.html

Hadi Rezaie

To get the ? help icon in a dialog, in the resource editor you need to set the More styles - Context help check box. You need to do this when the dialog resouce is selected, not one on the controls on the dialog. Make sure also that the System menu option is also checked in the styles tab.

Roger Allen
Sonork 100.10016

Thanks for your helps !

Wink | ;)

My month article: Game programming by DirectX by Lan Mader.
Please visit in: www.geocities.com/hadi_rezaie/index.html

Hadi Rezaie

Hi All,

I have a pretty simple CEdit subclass that paints its background with a texture bitmap. When I use it in multi-line mode, with more text than will fit in the window, scrolling upward doesn't cause WM_ERASEBKGND to be sent, and so the top lines are drawn over the old content (yuk!).

I've tried handling WM_CTLCOLOR- doesn't make any difference. Any ideas?

Thanks

NB

can't you refresh the whole window? It doesn't work?

hi lucky...

that would be a perfect solution, but in response to what message?

I think you could refresh all the window by handling the ON_SCROLL message or something like that

Hello,
I am trying to repaint just a small rect of my dialog.. The dialog has a Bitmap background and I have a static text (timer) that gets updated every second.. The problem is when it updated the static text it doesnt repaint the background so I get a bunch of numbers placed over the top of one another.. Looks really bad.. I can do a RedrawWindow() and it will repaint correctly but it repaints the whold dialog box (causes flickering) looks very anoying.. Im trying to just repaint a rect but I need the rect to be repainted just as well as if I were to do a RedrawWindow() on the whole dialog box.. this is what I have tried.

CRgn rgn;
rgn.CreateRectRgn(17,44,29,13);

CRect rect(17,44,29,13);

RedrawWindow(&rect, &rgn, RDW_INVALIDATE | RDW_ERASENOW | RDW_UPDATENOW);

I have tried several different flags but none of this seems to do the same thing as plain old RedrawWindow();

Any Ideas?

Rob

If you provide a region pointer, the rect pointer is ignored. Have you tried RDW_ERASE instead of RDW_ERASENOW, which would give you the defaults exactly as if you'd just done RedrawWindow(); ?

Christian

After all, there's nothing wrong with an elite as long as I'm allowed to be part of it!! - Mike Burston Oct 23, 2001

I changed the rect pointer to a null and used the RDW_ERASE with the RDW_INVALIDATE and it still doesn't redraw like RedrawWindow with out any params.. strange.

Not sure what this isn't working.

Rob