Thread using COleDispatchDriver always causes exception on second execution - C / C++ / MFC Discussion Boards

Re: Extra bytes between struct elements spoiling match between structs and binary file formats: cure found

Matthew Faithfull21-Dec-07 2:13

21-Dec-07 2:13

If you find that doesn't work for your whole project then you can set the alignment on individual types see here[^]. Setting global alignment to 1 may also cause performance issues, problems with calling certain APIs and the effects on COM are probably beyond my comprehension. Microsoft pretty universally assume that alignment will be 8 as that's the default for all MS Compilers since the dark ages so you may even have trouble calling stuff in the runtime with global 1 alignment.
Hey if software development was that easy everyone would be doing it Smile | :)

Nothing is exactly what it seems but everything with seems can be unpicked.

Indeed...

CPallini21-Dec-07 2:52

CPallini

21-Dec-07 2:52

Matthew Faithfull wrote:
Hey if software development was that easy everyone would be doing it

Indeed everyone is doing it, don't you read the posts?
Big Grin | :-D

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

[my articles]

Re: Indeed...

Matthew Faithfull21-Dec-07 3:04

Matthew Faithfull

21-Dec-07 3:04

CPallini wrote:
don't you read the posts?

No I take a random stab at what the question might by reading every second word of the title and then post a reply consisting of artfully rearranged phrases from one of 16 stock replies written for me by a team of genuine Irish code pixies I met in bar in Edinburough. It really saves a lot of time and effort and people seem to like it. Laugh | :laugh:

Nothing is exactly what it seems but everything with seems can be unpicked.

Re: Indeed...

CPallini21-Dec-07 3:15

CPallini

21-Dec-07 3:15

That must be one of the best of the stock
Laugh | :laugh:

PS: My regards to such a lovely town.
Smile | :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

[my articles]

Re: Extra bytes between struct elements spoiling match between structs and binary file formats: cure found

Mark Salsbery21-Dec-07 8:14

Mark Salsbery

21-Dec-07 8:14

That being generally a bad idea aside, didn't someone mention
that here[^] yesterday?

Good luck!
Mark

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

is such exception handling approach good?

George_George21-Dec-07 1:42

George_George

21-Dec-07 1:42

Hello everyone,

Suppose I have some objects created on local function stack (not on heap). And I allocate and free all the related resources in the constructor and destructor (e.g. memory and file handles). And I do not implement explicit exception handling code in the function for resource free purpose, and simply rely on destructor to free resources if exception occurs, that is,

1. when exception occurs and the exception triggers us to go out of current function stack to the caller to find exception handlers;
2. since objects are allocated on local stack, when exception triggers us to go out of current stack to its caller to find exception handler, the lifecycle of local objects on local stack will expire, and its related destructor will be invoked and free resources.

Pseudo code like this,

void func()
{
      Class1 inst1;
      Class2 inst2;

      ... // some operations

      return;
}

Does above code always safe? Are there any potential risks to leak resources?

thanks in advance,
George

Re: is such exception handling approach good?

Matthew Faithfull21-Dec-07 2:05

Matthew Faithfull

21-Dec-07 2:05

Yes, that's as safe as you make Class1 and Class2 except in one instance, a stack overflow. In all other cases I know of, provided you have an exception handler somewhere up the stack then the Unwind function will be called in the runtime which uses a bit of compiler magic to ensure that the destructors for inst1 and inst2 are called. In the case of a stack overflow exception you're pretty much dead in the water. There is the _resetstkoflw() runtime function but it won't prevent anything allocated on the heap in your Class1 and Class2 constructors being leaked.

Nothing is exactly what it seems but everything with seems can be unpicked.

Thread using COleDispatchDriver always causes exception on second execution

Streifenhoernchen21-Dec-07 1:42

Streifenhoernchen

21-Dec-07 1:42

In general, what the thread does is: Creating and sending an e-mail containing a file attachment using an Outlook or Lotus Notes client (if installed on the system).
Running the thread once always works fine, and it terminates correctly. However, when i try to run it for a second time, it throws an exception in MFC42.DLL, unfortunately not always at the same code line, but more or less randomly, esp. during manual debugging:

UINT CommonSendMailThread(LPVOID pParam)<br />
{<br />
   //pParam is a user-defined struct containing the necessary credentials<br />
   //like recipient address, file attachment path and name, and so on...<br />
<br />
   //a global variable sType defines the user's default mail client app<br />
   //user has "Outlook" as default<br />
   if (sType == "%OUTLOOK%") {<br />
      try {	<br />
         _DApplication OutlookHandle;	<br />
			<br />
         // Initialize OLE libraries<br />
         if (!AfxOleInit())<br />
            return 1;<br />
         else {   //try to find the installed version of Outlook<br />
            if (OutlookHandle.CreateDispatch("Outlook.Application.8") == FALSE) {<br />
               // check for Outlook 2000<br />
               if (OutlookHandle.CreateDispatch("Outlook.Application.9") == FALSE) {<br />
                  // check for Outlook XP<br />
                  if (OutlookHandle.CreateDispatch("Outlook.Application.10") == FALSE) {<br />
                     // Outlook ???<br />
                     if (OutlookHandle.CreateDispatch("Outlook.Application.11") == FALSE) {<br />
                        // Outlook ???????<br />
                        if (OutlookHandle.CreateDispatch("Outlook.Application.12") == FALSE) {<br />
                           return 1;<br />
         }}}}}}<br />
<br />
         // Outlook dispatch created successfully	<br />
         _DMailItem	newMail;<br />
<br />
         // create a new mail<br />
         newMail = OutlookHandle.CreateItem(0);<br />
<br />
         //fill the mail...<br />
         //(...)<br />
         //and send it			<br />
			<br />
         newMail.Send();<br />
<br />
         OutlookHandle.ReleaseDispatch();<br />
      }<br />
<br />
      catch(...) {<br />
         return 1;<br />
      }<br />
   } // OUTLOOK<br />
<br />
   //user has "Lotus Notes" as default<br />
   else if (sType == "%NOTES%") {<br />
      try {<br />
         if (!AfxOleInit())<br />
            return 1;<br />
<br />
         NOTESSESSION *pNotesSes = NULL;<br />
         NOTESDATABASE *pNotesDB = NULL;<br />
         NOTESDOCUMENT *pNotesDoc = NULL;<br />
         NOTESRICHTEXTITEM *pNotesRichTextItem = NULL;<br />
<br />
         // pointer to new NotesSession<br />
         pNotesSes = new NOTESSESSION;<br />
<br />
         if ( !pNotesSes )<br />
            return 1;<br />
<br />
         if ( pNotesSes == NULL )<br />
            return 1;<br />
<br />
         if (!pNotesSes -> CreateDispatch( "Notes.NotesSession" ))<br />
            return 1;<br />
	<br />
         if ( pNotesSes -> m_lpDispatch == NULL ) {		<br />
            delete pNotesSes;<br />
            return 1;<br />
         }<br />
<br />
         //Create and fill the mail...<br />
         //(...)<br />
			<br />
         pNotesDoc ->SEND(0, COleVariant(sRecipientAddress));<br />
         pNotesDoc ->REMOVE (0);<br />
<br />
         pNotesRichTextItem ->ReleaseDispatch();<br />
         pNotesDoc ->ReleaseDispatch();<br />
         pNotesDB ->ReleaseDispatch();<br />
         pNotesSes ->ReleaseDispatch();<br />
<br />
         delete pNotesRichTextItem;<br />
         delete pNotesDoc;<br />
         delete pNotesDB;<br />
         delete pNotesSes;<br />
      }<br />
<br />
      catch(...) {<br />
         return 1;<br />
      }<br />
   } // NOTES<br />
   else {<br />
      return 1;<br />
   }<br />
<br />
   //exit the thread<br />
   return 0;<br />
}

I'm totally confused and have no idea how to solve or even access the problem. Any hint or help is greatly appreciated!

Re: Thread using COleDispatchDriver always causes exception on second execution

Nathan Holt at EMOM21-Dec-07 7:43

Nathan Holt at EMOM

21-Dec-07 7:43

Member 4760200 wrote:
In general, what the thread does is: Creating and sending an e-mail containing a file attachment using an Outlook or Lotus Notes client (if installed on the system).
Running the thread once always works fine, and it terminates correctly. However, when i try to run it for a second time, it throws an exception in MFC42.DLL, unfortunately not always at the same code line, but more or less randomly, esp. during manual debugging:

I would look up the MFC implementation of the send mail command in CDocument, and adapt the code to my purposes, rather than sending it through Outlook or Lotus Notes. If I did need to do it that way, one of the first questions I'd ask is "What exception is being thrown?" Also, in general returning 1 is not adequate for handling unknown exceptions. Terminating the whole program is more reasonable. Finally, the random nature of the exception sounds like a race condition, and since it doesn't go away when you debug, I would guess that you are calling functions that are intended to be called from only one thread for the duration of the process. I'm sorry I can't be more helpful.

Nathan

Subclassing (using MFC) a wndow under explorer process

Nishad S21-Dec-07 1:38

Nishad S

21-Dec-07 1:38

Hi,

Isn't it possible to subclass a window in the explorer process, using CWnd::SubclassWindow() ?

My intention is to skin the systray clock.

What I did:

1. Created a MFC dll.
2. Injected it to the explorer process using "CreateRemoteThread - LoadLibrary" technique.
3. Took the window handle of systray clock in the dll's InitInstance.
4. Replaced the window proc using SetWindowLong.

These were successful, and in the replaced proc, I could do the custom draw by processing WM_PAINT.

The problem:

I derived a class from CWnd, say CMyClock. And subclassed the systray clock window with CMyClock object (member) instead of proc replacement. Now the explorer crashes.

I tried to debug the explorer process.

I found that subclassing is fine, and InitInstance completed successfully. After a very little time it crashed and the call stack was as follows...

	ntdll.dll!7c901230() 	
>	msvcr71d.dll!_CrtDbgBreak()  Line 93	C
 	msvcr71d.dll!_CrtDbgReport(int nRptType=2, const char * szFile=0x01b44c68, int nLine=384, const char * szModule=0x00000000, const char * szFormat=0x00000000, ...)  Line 427	C
 	mfc71d.dll!AfxAssertFailedLine(const char * lpszFileName=0x01b44c68, int nLine=384)  Line 28 + 0x14	C++
 	mfc71d.dll!AfxWndProc(HWND__ * hWnd=0x000f01c8, unsigned int nMsg=15, unsigned int wParam=0, long lParam=0)  Line 384 + 0x15	C++
 	MyClockDll.dll!AfxWndProcDllStatic(HWND__ * hWnd=0x000f01c8, unsigned int nMsg=15, unsigned int wParam=0, long lParam=0)  Line 53 + 0x15	C++
 	user32.dll!7e418734() 	
 	user32.dll!7e418816() 	
 	user32.dll!7e41b4c0() 	
 	user32.dll!7e41b50c() 	
 	ntdll.dll!7c90eae3() 	
 	user32.dll!7e4194d2() 	
 	user32.dll!7e41b530() 	
 	user32.dll!7e42d950() 	
 	user32.dll!7e418a10() 	
 	user32.dll!7e42dbbf() 	
 	user32.dll!7e42593f() 	
 	user32.dll!7e43a91e()

What could be wrong? Any suggestions or ideas?

Thanks in advance.

- NS -
[ODBaseBtn]

Reference are always lvalue?

George_George21-Dec-07 1:11

George_George

21-Dec-07 1:11

Hello everyone,

Is the conclusion correct? Both const reference and non-const reference are lvalue?

I think it is true and I can not find a sample which does not follow it.

thanks in advance,
George

Re: Reference are always lvalue?

Budric B.21-Dec-07 5:09

Budric B.

21-Dec-07 5:09

I suppose if you're returning a reference from a function then it's not an lvalue.

Re: Reference are always lvalue?

George_George21-Dec-07 19:16

George_George

21-Dec-07 19:16

Thanks Budric,

Could you show a sample please?

regards,
George

how to get the number of lines shown in editbox

rajneshmalik21-Dec-07 1:06

rajneshmalik

21-Dec-07 1:06

hi to all
i want to get the number of lines shown in editbox.
thank u

Re: how to get the number of lines shown in editbox

CPallini21-Dec-07 3:05

CPallini

21-Dec-07 3:05

Win32?
Look at EM_GETLINECOUNT message documentation http://msdn2.microsoft.com/en-us/library/bb761586.aspx[^]

MFC?
look at CEdit::GetLineCount method documentation http://msdn2.microsoft.com/en-us/library/bb761586.aspx[^]

Smile | :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

[my articles]

Datashowing problem want to get rid of from if-else statement

Y_Kaushik20-Dec-07 23:53

Y_Kaushik

20-Dec-07 23:53

Hello...guru's

I am writing a program in VC++ its database related application.
In this case i fetch data from Oracle database.using CRecordset class.

When i write below code
no_field = rs.GetODBCFieldCount();
while(!rs.IsEOF())
{
for(i=0;i<no_field;i++)
{
rs.GetFieldValue(i,sString);
if(i==0)
{
SetDlgItemText(IDC_EDIT_DATE1,sString);
}
if(i==1)
{
SetDlgItemText(IDC_EDIT_DATE2,sString);
}
if(i==2)
{
SetDlgItemText(IDC_EDIT_UPDT,sString);
}
}
sString.Empty();
rs.MoveNext();
}

Although above code is work fine.........
but i want to get rid of from if else condition.....This method is fine for fetching certain field from database .But if table contain 200 or more entity in a row then i need to write 200 or more if else condition...

Can any one give me berief idea how can i do this apart from this way.........

Thanks in Advanced

Regard's
Kaushik

Re: Datashowing problem want to get rid of from if-else statement

Hamid_RT21-Dec-07 0:02

Hamid_RT

21-Dec-07 0:02

Instead use of if you can use of switch.
Switch(i)
{
case 0:
break;
case 1:
break;
default:
break;
}

Re: Datashowing problem want to get rid of from if-else statement

Cedric Moonen21-Dec-07 0:13

Cedric Moonen

21-Dec-07 0:13

And how can he get rid of the 200 tests conditions by using a switch ? Unsure | :~

Cédric Moonen
Software developer

Charting control [v1.2]

Re: Datashowing problem want to get rid of from if-else statement

Cedric Moonen21-Dec-07 0:11

Cedric Moonen

21-Dec-07 0:11

Open the resource file and give adjacent Id's for your controls. This, way, you can simply do something like this:

SetDlgItemText(IDC_FIRST_CTRL_ID+i,sString);

Cédric Moonen
Software developer

Charting control [v1.2]

Re: Datashowing problem want to get rid of from if-else statement

Matthew Faithfull21-Dec-07 0:11

Matthew Faithfull

21-Dec-07 0:11

Two things you could do here.

Use a switch statement

<br />
switch i<br />
{<br />
  case 1:<br />
   //Do stuff<br />
   break;<br />
  case 2:<br />
    //Do other stuff<br />
   break;<br />
}<br />

but I wouldn't recommend that if you really have 200 fields and 200 controls on your dialog. If that's the case the easiest way is to ensure the values of your control id's are sequential and then do something like this

<br />
for(i=0;i<no_field;i++)<br />
{<br />
  rs.GetFieldValue(i,sString);<br />
  SetDlgItemText( BASE_FIELD_CONTROL_ID + i, sString);<br />
  sString.Empty();<br />
  rs.MoveNext();<br />
}<br />

you might want to use different ranges based on field/control types and use a switch to change the SetDlgItemText call.

Nothing is exactly what it seems but everything with seems can be unpicked.

Re: Datashowing problem want to get rid of from if-else statement

Y_Kaushik21-Dec-07 19:08

Y_Kaushik

21-Dec-07 19:08

Thanks for reply ....
I follow second method... give the control adjacent
like IDC_CONTROL , IDC_CONTROL+1, IDC_CONTROL+2, and so on...

and i am very near to solve problem...

Thanks again for reply to all's

Note : Is it possible for me to get control handle at run time.

Regard's
Kaushik

Dynamically providing version information to a exe

neha.agarwal2720-Dec-07 22:50

neha.agarwal27

20-Dec-07 22:50

Hi all,

Actually i want to give my exe, version number, copyright information dynamically. Is it poosible to do so.....

Re: Dynamically providing version information to a exe

jhwurmbach20-Dec-07 23:08

jhwurmbach

20-Dec-07 23:08

How dynamic is "dynamically"?

Here, our build-server includes a small, generated file with a version resource in the main resources of the project.
That way, the version number is set automagically.

Let's think the unthinkable, let's do the undoable, let's prepare to grapple with the ineffable itself, and see if we may not eff it after all.
Douglas Adams, "Dirk Gently's Holistic Detective Agency"

Re: Dynamically providing version information to a exe

C^hris L^osinger21-Dec-07 5:45

C^hris L^osinger

21-Dec-07 5:45

you mean the stuff that shows up in the Explorer Properties page after you right-click on the EXE's icon ?

no, that's not possible.

that stuff comes from examining the EXE file directly, not from executing the EXE in any way.

image processing toolkits | batch image processing

Checking the camera is connecte or not

Deepu Antony20-Dec-07 22:26

Deepu Antony

20-Dec-07 22:26

pls help me...

I am connecting a webcam to my computer thorugh usb port.can anybody help me to write a code in vc++ or c++ to check whether the camera is connected or not.

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