Re: AfxGetApp() returns NULL

From:

"Sheng Jiang[MVP]" <sheng_jiang@hotmail.com.discuss>

Newsgroups:

microsoft.public.vc.mfc

Date:

Fri, 7 Dec 2007 20:33:40 -0600

Message-ID:

<ORLT8pTOIHA.5208@TK2MSFTNGP04.phx.gbl>

Put a breakpoint in your App's constructor (add one if you don't have it).
Run your application. If the error happens before your App's constructor is
called, then you have a bug. Most likely you are trying to access the app in
another global variable's constructor, and the sequence of constructing
global variable is undefined. Redesign your applition so your global
variables 's constructors don't rely on the existance of the app object.

--
Sheng Jiang
Microsoft MVP in VC++
"LogicMan" <garybell.home@gmail.com> wrote in message
news:953f6a25-a0be-4803-8cdf-5e36b0cb4235@b15g2000hsa.googlegroups.com...

Hi,

While I've been programming for a number of years I'm fairly new to
MFC (and C++ for that matter). I have inherited a rather large MFC
app that had been done in VS2003. I recently moved it to VS2005.
While I was able to make it compile with much troubleI immediately ran
into major problems running the application. They manifested as
access violations and were all centered around calls to AfxGetApp() to
access member variables of the main application object. It's not
always the same place in the application, but it's always the same
sequence. AfxGetApp() ends up calling the routine below. When the
if(pState->m_pModuleState != NULL) is true then it ends up returning a
NULL value. When it falls through to use the
_afxBaseModuleTate.GetData() then all is well. This is all in the
main app, not a DLL, although there are quite a few DLLs that get
referenced (as in process COM objects).

I'm a bit over my head on this. I've been able to make most problem
go away by replacing any AfxGetApp()-> references with thisApp.
references. but obviously there's stuff going on that Is there some
direction I can take to help solve this? Is there something
inherently different in VS2005 than VS2003 that I should be aware of
as it pretains to how state is stored, etc?

Any direction would be greatly appreciated. Thanks!!

AFX_MODULE_STATE* AFXAPI AfxGetModuleState()
{
_AFX_THREAD_STATE* pState = _afxThreadState;
ENSURE(pState);
AFX_MODULE_STATE* pResult;
if (pState->m_pModuleState != NULL)
{
// thread state's module state serves as override
pResult = pState->m_pModuleState;
}
else
{
// otherwise, use global app state
pResult = _afxBaseModuleState.GetData();
}
ENSURE(pResult != NULL);
return pResult;
}