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My recent work content involved some exception handling, __try/__except to be specific. And the following is the questions that confused me.
int filter()
{
puts("Filter()");
return EXCEPTION_EXECUTE_HANDLER;
}
int _tmain(int argc, _TCHAR* argv[])
{
int a = 1;
int *p = NULL;
char s[10];
__try
{
__try
{
a = 2;
*p = a;
puts("After exception raised");
a = 3;
}
__finally
{
puts("Finally");
a = 4;
}
}
__except(filter())
{
puts("_except");
a = 5;
}
sprintf(s, "%d", a);
puts(s);
_getch();
return 0;
}
My questions focused on the return statement in exception filter function:
if it is return EXCEPTION_EXECUTE_HANDLER,why the statement a = 3; never gets excuted?
if it is return EXCEPTION_CONTINUE_EXECUTION,why the filter keeps getting called. according to MSDN EXCEPTION_CONTINUE_EXECUTION The system stops its search for a handler and returns control to the point at which the exception occurred.return control to *p = a? only to cause another same exception? what's the point here?
if it is return EXCEPTION_CONTINUE_SEARCH, the system keeps searching for exception handlers on and on and on for access violation? until the handlers were exhausted? another seemingly endless function call?
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LiYS wrote: if it is return EXCEPTION_EXECUTE_HANDLER,why the statement a = 3; never gets excuted?
A quote from MSDN: "A __finally statement does not block searching for an appropriate exception handler". You raise the exception with the following statement:
*p = a;
The system will then looks for an exception handler calling any __finally blocks on the way (actually this isn't quite true but it's good enough for now). When it gets to the __except block the filter expression returns EXCEPTION_EXECUTE_HANDLER so it enters the block and the exception is handled.
LiYS wrote: if it is return EXCEPTION_CONTINUE_EXECUTION,why the filter keeps getting called.
The idea of EXCEPTION_CONTINUE_EXECUTION is that the code first takes some action to correct the problem then execution is resumed and the operation is retried: you are performing no such correction thus the problem keeps recurring. In short everything is working as it should. Note that the __finally handler will not be called in this case (this is where real life differs slightly from my explaination as alluded to in my, "this isn't quite true" comment above).
LiYS wrote: If it is return EXCEPTION_CONTINUE_SEARCH, the system keeps searching for exception handlers on and on and on for access violation?
If you return this you're telling the system that the particular __except block should not be entered and to continue searching for a handler. If no handler is encountered that handles the exception execution is aborted.
Steve
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Hi all,
Are you concentrating?
Yes, good!
Please read this carefully
An example of my problem is I have three controls.
- Control A
- Control B1
- Control B2
I want to be able to either B1 or B2 to be a child window of A depending on how I set the properties. Of course I know A is child window. when I place it on the a driver (demo) app, it crashing my system. I want to know to do this safely?
Many thanks,
alton
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Hi Alton!
If you find the part below hard to understand, please let me know and I'll repost typing it slower. 
Alton Williams wrote: Of course I know A is child window. when I place it on the a driver (demo) app, it crashing my system.
How does it crash your system? Error messages? Some info from debug sessions?
The "system" could crash from a zillion reasons, give or take a few, it's quite hard to guess what your problem is.
--
Roger
It's supposed to be hard, otherwise anybody could do it!
Regarding CodeProject: "resistance is pointless; you will be assimilated"
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Hi Roger,
Thanks for your prompt reply!
Roger Stoltz wrote: How does it crash your system? Error messages? Some info from debug sessions?
When I build and register the control. When I place it on another form (in VB) or Dialogue box (in VC++) for testing. it seems to bring down VB or VC++. If I'm lucky if my final app comes down or doesn't respond at run-time.
Is that any clearer?
Alton
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Alton Williams wrote: When I build and register the control.
I interpret this as you get an assertion or runtime error when you try to register the component after a successful build. Correct?
What happens if you try to register the component outside DevStudio? If it crashes even then I suggest you try to debug the component by selecting RegSvr32.exe as the executable for debug session, provide the complete path to your debug-built component as argument and "run" your component (F5). Put a breakpoint inside DllRegisterServer() and step through the registration call chain.
If you don't get any clues from this exercise; post again and describe what happens, what error messages you're getting and where.
Alton Williams wrote: When I place it on another form (in VB) or Dialogue box (in VC++) for testing. it seems to bring down VB or VC++. If I'm lucky if my final app comes down or doesn't respond at run-time.
If the registration isn't successful you may get various errors when you try to use the component, e.g. inserting it to a client or running the final app.
In other words: let's fix the registration first if it doesn't work.
--
Roger
It's supposed to be hard, otherwise anybody could do it!
Regarding CodeProject: "resistance is pointless; you will be assimilated"
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Hello Roger,
Sorry I've a while to answer your question
Roger Stoltz wrote: Alton Williams wrote:
When I build and register the control.
I interpret this as you get an assertion or runtime error when you try to register the component after a successful build. Correct?
No, Rog! It builds and get registered perfectly when I place the end result onto another project be it VC dialogue or a VB form the aproppriate developer app (MSVC6 or MSVB6) crashes. I if it would be a HWND problem
I'll explain the issue more clearly.
I've created three controls;
- A control called child1ctrl which is a subclass of "EDIT"
- Another called child2ctrl is that of "STATIC"
- A third one called holderctrl which isn't subclassed
Firstly, I design controls 1 & 2 individually either as single project or two projects (that's not relevant). Naturally it builds and registers the two controls ok. At this stage when add either (1 or 2) to other projects. Works perfectly.
It's when I am design control no 3. I'm what is the cause for concern
I do the follow
- I go through the wizard
 - I add controls (1 and 2) to the project and it generates the wrapper
classes.(CChild1 & CChild2) - I make these as two member variables one of each class.
- I write code to create the two child windows
I have no problems with build and the control registers with no problems. Its when I add HolderControl onto other projects I drag and drop it on a diaglogue box and crashes VC++ (msdev.exe). Likewise I do it on a for VB (VB.exe) comes down.
To begin with I wrongfully wrote code to create (1 & 2) in WM_CREATE.
class CHolder{
virtual void PreSubclassWindow();
private:
CChild1 m_ctrl1;
CChild2 m_ctrl2;
BOOL m_bFlag
Then
void CHolderCtrl::PreSubclassWindow()
{
m_bFlag = m_ctrl1.CreateControl(clsid, NULL, dwStyle, rect, this)
&& m_ctrl2.CreateControl(clsid, NULL, dwStyle, rect, this);
COleControl::PreSubclassWindow();
}
On debugging what is causing the crashing seems lie with the first call to create for the first "window" so the second call doesn't happen.
MS Calendar Control 8.0 dosen't behave like this. I has two child ComboBoxes and 50 Statics on it.
I don't if I'm clearer now.
I going to repost the question on this an other forums, until I get an answer.
Thanks for your help nonetheless.
Alton
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Alton Williams wrote: On debugging what is causing the crashing seems lie with the first call to create for the first "window"
Seriously Alton, you have to investigate your own code better than that or no one will ever bother to answer your vague question.
It's perfectly allright to have an ActiveX control as a container for another ActiveX control, you don't have to doubt that.
The reason why this doesn't work in your code is because you've either removed some important stuff or haven't written the important stuff yet.
It's also not very clear what base classes you're subclassing from or why. If you're using MFC to create your controls, the only class you should derive from is COleControl; anything else I would consider highly suspicious and to be removed at once if not given a lot of thought ending with "I've-read-alot-about-it-and-I-know-it's-the-correct-way-to-do-it".
I suggest you start over with the CHolderCtrl and create it with the ActiveX control wizard.
For every step you take building the functionality of the CHolderCtrl, you should test it with "ActiveX Control Test Container" that ships with MSVC.
Don't add the two contained ActiveX controls to CHolderCtrl until the last step. Make sure they can be inserted in an ordinary ActiveX control container before attempting to add them to CHolderCtrl.
Alton Williams wrote: Its when I add HolderControl onto other projects I drag and drop it on a diaglogue box and crashes VC++
This feels like the ActiveX control hasn't got all the required interfaces implemented as needed for it to an ActiveX control container.
Have a look here[^] for required interfaces depending on what functionality you want to support.
Alton Williams wrote: MS Calendar Control 8.0 dosen't behave like this. I has two child ComboBoxes and 50 Statics on it.
Now, this sentence really disturbs me since it makes me wonder if you're under the impression that comboboxes, edit and static controls are ActiveX controls. 
Just to tie up loose ends: comboboxes and static controls are not ActiveX controls!
On the other hand, perhaps this is exactly what you're after; an ActiveX control that looks like a dialog (or similar) with some CEdit/CStatic controls within the window....
If this is the case, you should have a member variable for each control on your window and simply call e.g. CEdit::Create() when you want to create a CEdit control.
Alton Williams wrote: I going to repost the question on this an other forums, until I get an answer
Well, perhaps not this question, you should investigate your code further and be more precise. But by all means: repost and you might get more replies since this thread is old and probably won't be read by anyone but me.
Alton Williams wrote: Thanks for your help nonetheless
You're welcome! ![Rose | [Rose]](https://codeproject.global.ssl.fastly.net/script/Forums/Images/rose.gif)
--
Roger
It's supposed to be hard, otherwise anybody could do it!
Regarding CodeProject: "resistance is pointless; you will be assimilated"
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I want to reproduce the sliding creation effect of a Window. The Window should slide when it is visible. I mean, first 10% of the width of the window should be visible, then 20% and so on. This must have a sliding effect. I have achieved it through by using regions. I am posting the code here. Can anyone suggest a better way?
The code is modified from Jaime Olivares' [^] article on Appbars.
void SlideWindow(CPoint StartPoint, BOOL Right2Left)<br />
{<br />
int nWinWidth = 500 ;<br />
int nWinHeight = 100 ;<br />
unsigned int t; <br />
int x ;<br />
int maxdelay = 5; <br />
float step = nWinWidth / 10.0f; <br />
HRGN hRgn ;<br />
SetWindowPos(HWND_TOP, StartPoint.x, StartPoint.y ,nWinWidth, nWinHeight, 0) ;<br />
<br />
for (int i=0, delay=maxdelay; i<=10; i++, delay+=2) <br />
{<br />
t = ::GetTickCount() + delay;
x = StartPoint.x - (int)(i*step) * (Right2Left?1:-1);
if(Right2Left)<br />
{<br />
hRgn = CreateRectRgn(0, 0, (int)(i*step), nWinHeight) ;<br />
SetWindowRgn(hRgn , FALSE ) ;<br />
DeleteObject( hRgn ) ;<br />
hRgn = NULL ;<br />
}<br />
else<br />
{<br />
hRgn = CreateRectRgn(0, 0, nWinWidth - (int)(i*step), nWinHeight) ;<br />
SetWindowRgn(hRgn , TRUE ) ;<br />
DeleteObject( hRgn ) ;<br />
hRgn = NULL ;<br />
} <br />
SetWindowPos(HWND_TOP, x, StartPoint.y, nWinWidth, nWinHeight, SWP_SHOWWINDOW);
<br />
while (::GetTickCount()<t)
::Sleep(15); <br />
}
---
With best regards,
A Manchester United Fan
The Genius of a true fool is that he can mess up a foolproof plan!
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hii,
Can any one please find the relevant registry keys for the local security Settings( \controlpanel\administrative tools\local security settings\account policies ). I need to set the minimum password length for windows,and set the account threshold and duration.
I am using Visual Basic.If i could locate the relevant registry keys,then
I can modify these settings programmatically using registry.
Can any one suggest me how i can set these settings programmatically??
any links or information regarding their registry entries would be useful for me.
Thanx
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I am developing a sourcefilter to decode 3gp songs. First, I built 3gp source code into dll, then, I loaded those dll in the filter. For example, I used
FileWrapper_Open(*char)
to open the 3gp file which is in the dll, but there is an error when running to this code. The error message is
'Unhandled exception at 0x100158dc (SourceFilter.ax) in graphedt.exe: 0xC0000005: Access violation writing location 0xbaadf069.'
I am not familiar with using dll. In developping the filter, I just included the header files of dll, and put dll in the same directory with the filter. Thanks for your help.
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It's difficult to say. You try to write memory somewhere you shouldn't. Try to use your debugger (press F5 and F9 to set breakpoints) to locate the problem. If you want to debug your dll, you will need to associate a exe that will call the exported functions you want to test (this is done in the project settings).
Cédric Moonen
Software developer
Charting control
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Thanks for your help. I debugged the code (F5, and set breakpoints), and got the error message, no further information. I tested the dll before I added them into filter (built another program to test it), and it ran well. As you said to debug dll, how to set the project to test it? Thanks.
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The value 0xbaadf00d is often used to fill memory to indicate that the data is bad or not initialised; note that is looks like the words, "bad food". If you do a search for this you get the following webpage[^]. It looks like you may be using uninitialised data. Note that 0xbaadf069-0xbaadf00d = 0x5c. This address could have been arrived at by using the value as a pointer and using it to access a member at offset 0x5c into a structure/class.
Steve
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thanks. I solved the problem although it is not a good method. Actually, as I used those dll decoding 3gp songs, I wrapped them (variable, functions) in a class, and got the error message. Now I used them as globle variables (it is not a good way), no such error. Thanks for your information.
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I want to be able to hide or password protect folders. How is it done?
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nat2kus wrote: How is it done?
Access Control Lists (ACL).
"The largest fire starts with but the smallest spark." - David Crow
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Our application needs to check if there's a CD inserted in the CD player.
Functions such as GetVolumeInformation() or GetFileAttributes() take too long.
Is there a faster way? I can see windows (XP) showing a "CD cursor", so there is somewhere inside windows a service that has detected a CD....
I hope someone knows where this information can be found.
Paul Visser
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Have you tried something like mciSendString("status cdaudio media present", ...)?
"The largest fire starts with but the smallest spark." - David Crow
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Thanks for the advice. It does make testing faster, certainly in the "false" cases when no CD is present in the drive.
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From my Win xP station where I have connected USB printer, I am not capable to print from my dos application. How can I Do to print to my USB Printer from DOS Application.
I learn my self
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You will have to do a "Net Use LPT..." type command to establish a correlation between a DOS-accessible device and the printer device name. This needs to be done either as a shell command prior to startup of your app (IE: batch file startup) or as part of a custom DOS box with special autoexec.bat.
onwards and upwards...
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I'm trying to find the best way to update my CView's when information in my CDocument changes. Right now I'm using the following method:
CMDIFrameWnd *pFrame = (CMDIFrameWnd*)AfxGetApp()->m_pMainWnd;<br />
CMDIChildWnd *pChild = (CMDIChildWnd *) pFrame->GetActiveFrame();<br />
CAESView *pView = (CAESView *) pChild->GetActiveView();<br />
<br />
pView->SendMessage(UWM_UPDATE_VIEW, 0, 0);<br />
This works fine but it only updates the active view. How can I update all views that are related to the document, whether they are active or not?
Thanks.
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Thanks Cedric. I didn't realize it was that simple. It was not mentioned in any book I have. I guess I need to buy some new books!
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