C / C++ / MFC

Exception with CFileDialog (MFC)

22-Jan-11 6:24

I have no experience of Flash, so I am unable to make any further suggestions.

I must get a clever new signature for 2011.

Le Duc Anh21-Jan-11 14:17

21-Jan-11 14:17

Hi everyone! I had the following lines of C++ code in my program

CFileDialog dialog(true);
CString strFileName=L"";
INT_PTR nResult = dialog.DoModal();
if(nResult == IDOK)
 // Exception spotted here
 // Debug information gives me --&gt; dialog = {CFileDialog hWnd=0x00000000}
 // What's the heck?
 strFileName=dialog.GetFolderPath();

The problem is: When I execute the program on a PC running Windows XP, there always have an ugly exception which I don't know why it happened. But everything's fine when I copied it to another PC running Windows 7.

I'm desperate. Would you guy please tell me why?

anhld

Andrew Brock21-Jan-11 15:57

21-Jan-11 15:57

The hWnd=0x00000000 is probably due to clean-up code.
As for the exception, could you tell us what it is. What code and/or message.

If you go to Debug>Exceptions and tick everything, it should break the debugger the moment the exception is thrown, so you can see what is causing it.
Once you have found the source, reset the exceptions filter (there should be a Reset All button in the dialog) otherwise they will annoy the heck out of you

Le Duc Anh21-Jan-11 17:18

21-Jan-11 17:18

I captured the context in an image below Sigh | :sigh:

Here the image

anhld

Andrew Brock21-Jan-11 17:23

21-Jan-11 17:23

MSDN[^] says:
The dialog box must have been created with the OFN_EXPLORER style; otherwise, the method will fail with an assertion.

You need to create the dialog like

CFileDialog dialog(true, NULL, NULL, OFN_HIDEREADONLY | OFN_OVERWRITEPROMPT | OFN_EXPLORER);

Le Duc Anh21-Jan-11 17:54

21-Jan-11 17:54

Sorry! It doesn't work. Frown | :(

anhld

Andrew Brock21-Jan-11 18:13

21-Jan-11 18:13

Perhaps i should have read the next line on that page[^].
"You can call this method only while the dialog box is being displayed. After the dialog box has been closed, this function will no longer work, and the method will fail with an assertion."

Not sure why it works on Windows 7, but you can instead use

strFileName = dialog.GetPathName(); //get the full path including the file name
strFileName = strFileName.Left(strFileName.ReverseFind(_T('\\')) + 1); //remove everything after the last slash

That is just example code, and you should add error checking into it to ensure there is a '\' character

Le Duc Anh21-Jan-11 18:19

Another basic debug question - how to debug OpenCV dll from my application.

21-Jan-11 18:19

Yeah! You're right! I should read MSDN carefully before asking this question. Anyway, thank you so much!

anhld

Vaclav_21-Jan-11 3:41

Re: Another basic debug question - how to debug OpenCV dll from my application.

21-Jan-11 3:41

Hello debug experts.

<b></b>I'll fess-up before I get flamed by someone here..
I did posted this in OpenCV group without success.

<b></b>This is basic dll debugging process I do not know how to do.

I need to debug , step thru, OpenCV function and I just cannot figure out the mechanics.

I put cv dll (dsp) as main project and then I added my application to the workspace.
I set a break point at the cv function entry in my application and then execute the cv dll.

However, I just cannot step into the cv dll function to check the code progress.
F11 goes right over the function.

What bugs me is that I can step thru other OpenCV code (Haar training) without a problem!

Can it be done and dhow ??
What am I missing??

Using VC6.0 , both - dll and my app - are configured for debug. No compiler or linker errors.
My app is linked to the debug library of the cv dll.
The application runs, sort of - bogus Haar objects are being detected.

Thanks for you help, it is as always appreciated.
Cheers Vaclav

Richard MacCutchan21-Jan-11 5:03

Re: Another basic debug question - how to debug OpenCV dll from my application.

21-Jan-11 5:03

Try rebuilding the complete project (application and DLL) in Debug mode and see if that works.

I must get a clever new signature for 2011.

Vaclav_21-Jan-11 5:15

Re: Another basic debug question - how to debug OpenCV dll from my application.

21-Jan-11 5:15

Richard,
found out that the function I am after is not in cv but in cvaux.
Added all relevant libraries and dependencies, rebuild all with success.

Still no go.

The question is - do I need to link the correct debug libraries?
Right now I have a mix of release and debug.
I'll do that next anyway.

What about the preprocessor's NDEBUG #define?

The functions I can step thru are in debug libaries and have the NDEBUG defined.

Thanks
Vaclav

Vaclav_21-Jan-11 5:32

Re: Another basic debug question - how to debug OpenCV dll from my application.

21-Jan-11 5:32

Richard,
noticed difference between project settings - the one which works has a "Link" tab option and the one which does not work - cvaux has a tab "library". No Link.
They both have _DEBUG in various places , no more NDEBUG.
Vaclav

PS Here are the library links. Both are set for debug option and cvhaartraining lets me step thru and the cvaux (both cvaux or cvaud) won't do it.

#pragma comment(lib,"G:\\Program Files\\OpenCV\\lib\\cvhaartraining")
#pragma comment(lib,"G:\\Program Files\\OpenCV\\lib\\cvauxd")

Thanks for helping me. I am stuck!

Richard MacCutchan21-Jan-11 6:23

Re: Another basic debug question - how to debug OpenCV dll from my application.

21-Jan-11 6:23

I can only assume that the cvauxd library should be a Debug build. You need to recheck all the project settings (Compiler and Library tabs) to ensure that they are creating all the Debug information required.

I must get a clever new signature for 2011.

Vaclav_21-Jan-11 8:10

Re: Another basic debug question - how to debug OpenCV dll from my application.

21-Jan-11 8:10

Yes, OpenCV designates debug libraies wiht suffix "d". Clever but I had to ask!

I think I need to check if these libraries are the ones I am actually linking to.

Right now I chaged to cxcored and getting this error which I totally do not know how to troubleshoot.
HEAP[Open....exe]: Invalid Address specified to RtlValidateHeap( 1e20000, b570450 )

What is realy strange this "cvhaartraining" dll compiles and builds a library without telleing me if it is debug or release.
I bet I am missing where it should go, but it works!
....
--------------------Configuration: cvhaartraining - Win32 Debug--------------------
Compiling...
cvboost.cpp
cvcommon.cpp
cvhaarclassifier.cpp
cvhaartraining.cpp
OpenMP not defined
cvsamples.cpp
Creating library...
--------------------Configuration: cv - Win32 Debug--------------------

.....
And that is the dll I can step thru!!!

And this is "normal" output

Generating Code...
Linking...
Creating library ../../lib/cvd.lib and object ../../lib/cvd.exp

I guess I'll go over all the options again!

Thanks for your input.

Richard MacCutchan21-Jan-11 9:16

Re: Another basic debug question - how to debug OpenCV dll from my application.

21-Jan-11 9:16

Vaclav_Sal wrote:
builds a library without telleing me if it is debug or release.

That is fairly normal. It is up to you to select the appropriate configuration to build and ensure that all the options are set correctly. As this is a third party product that I have never worked with I cannot make any better suggestions.

I must get a clever new signature for 2011.

Andrew Brock21-Jan-11 14:57

OpenGL and Live Video CDC.

21-Jan-11 14:57

1. Make sure the debug configuration is selected. Debugging works in Release mode but not as good
2. Check which library you are linking against. It should be cvd.lib (the main part is that you are lining against XXXd.lib for the debug libraries
3. Check the project properties for the DLLs to make sure debugging information is getting generated. I don't know where this is in VC6, but in VC9 is is Project Properties>Linker>Debugging>Generate Debug Info
4. Insert a breakpoint early in your code for the .exe you are testing it with. the first line of main() would be a good place
5. Check the loaded modules (in VC9 it is Debug>Windows>Modules) and make sure the right versions of the DLLs are loaded in (XXXd.dll)

GAJERA21-Jan-11 0:57

GAJERA

21-Jan-11 0:57

Hi all

I have two view ,Opengl and Live Video (Which convert live video data to image and show on CDC).
The 3D image draw in Opengl with different 3D point and draw in video CDC(convert 3D to 2D point).
Here My problem is how to draw 3D image in 2D live video CDC?.It should be show like OPengl with different shade,color,Blending and all feature which is provide by OpenGL.

AnyOne suggest the way for achive this thing.

Thanks

How to start debugging from application? [modified]

rrrado20-Jan-11 23:27

20-Jan-11 23:27

My application (32 bit) starts next process instance of itself. In new process I need to start debugging so I'm using __asm int 3; It worked good in WinXP/VS2008, it stopped the app and gave me selection whether start new VS instance or use existing VS instance to debug. I've switched to Win 7 64 bit and it does not work anymore. It offers nothing, app just hangs for some time, then exits, I cannot even attach debugger to the process manually. How can I solve this?
Thank you.

In VS options, the "Jst-in-time" I have all options active (managed,native,script)

modified on Friday, January 21, 2011 5:46 AM

Andrew Brock20-Jan-11 23:36

20-Jan-11 23:36

try

#include "CrtDbg.h"
//code ...
_CrtDbgBreak();

rrrado20-Jan-11 23:45

20-Jan-11 23:45

the same result Frown | :(

Andrew Brock21-Jan-11 0:38

21-Jan-11 0:38

_CrtDbgBreak() is a valid function under Win64. Perhaps it expects a debugger to be attached.

Perhaps you could use something like:

while (!IsDebuggerPresent()) {
	Sleep(1000);
}

It is quite a hack up, but if it is just for testing it doesn't really matter.

rrrado21-Jan-11 1:26

21-Jan-11 1:26

Thank you for tip.

while (!IsDebuggerPresent()) {
	Sleep(1000);
}
__asm int 3;

works, but now I have to attach debugger to correct process manually Frown | :(

It would me more convenient if it would work like before so other ideas are still welcome Smile | :)

Andrew Brock21-Jan-11 1:35

21-Jan-11 1:35

Perhaps it is something wrong with your JIT settings.
I just ran

#include <Windows.h>
#include <CrtDbg.h>

int main() {
	OutputDebugString(TEXT("Hello\n"));
	_CrtDbgBreak();
	OutputDebugString(TEXT("World\n"));
	return 0;
}

Compiled in debug mode on VS 2008. It came up with the crashed message, 1 of the options was to debug the program.

This gave me an idea, if _CrtDbgBreak() doesn't work for you, just crash you program and attach the JIT then.
Once attached you can just drag the instruction pointer (the yellow arrow to the left of the code) to the next line and hit continue.

Something simple to crash your program would be

char *p = NULL;
*p = 0; //Write 0 to an invalid address

rrrado21-Jan-11 2:44