Assertion From SendNotifyMessage

ForNow

I am doing Interprocess communication between a C console app and C++ Windows app The C console app is the parent process I have the Window handle (main window MainFrame) of the C++ child app I use SendNotifymessage to tell the child app that console app has data for it in shared storage The First time I do this all is well The Second time around I have created a modless dialog box with a Crichedit control it is at this time where I get a asseration from the SendNotifyMessage in the console C app The assetration is dlgcore.cpp at the parent GetSafeHWnd

	lpDialogTemplate = (DLGTEMPLATE\*)GlobalLock(hTemplate);

	// setup for modal loop and creation
	m\_nModalResult = -1;
	m\_nFlags |= WF\_CONTINUEMODAL;

	// create modeless dialog
	AfxHookWindowCreate(this);
	hWnd = ::CreateDialogIndirect(hInst, lpDialogTemplate,
		**pParentWnd->GetSafeHwnd(), AfxDlgProc);

#ifdef _DEBUG**
dwError = ::GetLastError();
#endif
}
CATCH_ALL(e)
{

Jochen Arndt

pParentWnd is NULL or the window has not yet been created (it's HWND member is NULL). I can give no more help because you did not show the relevant code parts (the posted code seems to be MFC source).

Lost User

Why are you using pParentWnd->GetSafeHwnd() to get your HWND? You should just use GetSafeHwnd() on its own.

ForNow

The Hwnd is a main Window it is set to a value i'll go into assembly mode and double check

ForNow

thing is I don't know how the code got to dlgcore.cpp The Hwnd is a MainWindow Okay thanks

Lost User

It gets to dlgcore by virtue of your call to SendNotifyMessage, at which point it asserts because the handle you sent it is not valid.

ForNow

But the Window Handle is a Main or Mainframe Window I did a FindWindow api call To get the handle As the parent is a C console app and it did work once before I created the modless dialog box in the child process

Lost User

But you are calling pParentWnd->GetSafeHwnd() in a console app which makes no sense. What does pParentWnd point to?

ForNow

Hi I am at work now however the only thing I can think of at this point is that I have to use DuplicateHandle to make the child main window accessible to the parent

Lost User

No, you just need to find its handle by one of the enumerate functions, or get the child to pass it back in some way. A handle is just a pointer used to identify a Window so you can send messages to it. To be honest, I am not exactly clear about what you are trying to do beyond the basic SendMessage function.

ForNow

"EnumThreadWindows" My questions in Windows is a threadID unique throughout Windows Thanksp

Lost User

I would assume yes, since in the case of EnumThreadWindows, the threadid is the only information Windows needs to return the information.

ForNow

Richard got the same assertion I believe this has to do with sharing window handles between threads I am going to use duplicate handle and see if that resolves the issue Thanks

Lost User

ForNow wrote:

I believe this has to do with sharing window handles between threads

I don't think so. You should be able to send a message to a Window from anywhere.