C / C++ / MFC

3-Dec-09 0:38

Hello All
I getting exception while I use

mysql_fetch_field

.I use debug then I found when table rows is more than 229000 then Iam getting exception in this line

field1=mysql_fetch_field(res1);

Unhandled exception at 0x10010d74 in SQLconvert.exe: 0xC0000005: Access violation reading location 0x00000040.

Call stack shows

libmySQL.dll!10010d74() 	
 	[Frames below may be incorrect and/or missing, no symbols loaded for libmySQL.dll]	
>	SQLconvert.exe!CSQLconvertDlg::EnumRow(ATL::CStringT<char,StrTraitMFC<char,ATL::ChTraitsCRT<char> > > tab="sheet1")  Line 1400 + 0xc bytes	C++
 	SQLconvert.exe!CSQLconvertDlg::Convert()  Line 1147	C++
 	SQLconvert.exe!readThread(void * p=0x0012f254)  Line 56	C++
 	SQLconvert.exe!_AfxThreadEntry(void * pParam=0x0012e5c0)  Line 109 + 0xf bytes	C++
 	SQLconvert.exe!_callthreadstartex()  Line 348 + 0xf bytes	C
 	SQLconvert.exe!_threadstartex(void * ptd=0x003fd628)  Line 331	C
 	kernel32.dll!7c80b699()

code is here

QueryResultsPtr Qry;
MYSQL_FIELD	*field1;
MYSQL_RES	*res;
enum enum_field_types type;
	if (!mysql_query(conn," SELECT * FROM tes")) 
	{
		res = mysql_store_result(conn) ;
		int numrows = (int)mysql_num_rows(res);
		int numflds = (int)mysql_num_fields(res);
		
		while (row = mysql_fetch_row(res)) 
		{
			
			res1=mysql_list_fields(conn,tab,"%");
			for(long y=0; y<numflds; y++)
			{
				
				str2.Empty();
				field1=mysql_fetch_field(res1);
				if(field1->flags & AUTO_INCREMENT_FLAG)
					continue;
				str2+=(LPTSTR)row[y];
				type=field1->type;
				
			}
}
}

includeh103-Dec-09 1:26

3-Dec-09 1:26

It may be a bug, but I don't think that you need to SELECT * from the huge table, why do not where something to reduce fetched rows?

try to use mysql_use_result() rather than mysql_store_result() to see if the problem can be fixed.

BTW: mysql_num_rows() is invalid if using mysql_use_result().

Rajesh R Subramanian3-Dec-09 1:26

Rajesh R Subramanian

3-Dec-09 1:26

MsmVc wrote:
int numrows = (int)mysql_num_rows(res);

res is an uninitialised pointer and is probably pointing to some random memory location. If mysql_num_rows() attempts to write anything to the memory pointed by res, the Universe will end.

Why can't you try this instead?

MYSQL-RES res;
...//bunch of stuff
mysql_num_rows(res);

That applies to other pointer variables as well.

“Follow your bliss.” – Joseph Campbell

MsmVc3-Dec-09 1:30

3-Dec-09 1:30

sorry

res is an initialised Globel MYSQL_RES *res;

Rajesh R Subramanian3-Dec-09 1:33

Rajesh R Subramanian

3-Dec-09 1:33

MsmVc wrote:
res is an initialised Globel MYSQL_RES *res;

The results will still be the same, won't it be? I do not know if the method that accepts that particular pointer will do a write operation to it, or probably call some method on it if it's a class object.

Either ways, how do you expect an uninitialised pointer to work? Confused | :confused:

Try creating the variable on the stack and use it instead.

“Follow your bliss.” – Joseph Campbell

MsmVc3-Dec-09 1:40

3-Dec-09 1:40

sir
my code is working fine when table rows is less than 229000.I am getting error when table rows is more than 229000.
So there is no need to discusses about res is an initialised or uninitialised.Matter is why

mysql_fetch_field(res1);

generating exception if table rows is more than 229000.
Plz help me

includeh103-Dec-09 2:10

3-Dec-09 2:10

did you try to use mysql_use_result() rather than mysql_store_result()?

do you know the difference of the 2 functions? why do not try it?

MsmVc3-Dec-09 17:22

Getting problem with RegisterShellFileTypes() in MFC Dialog based application. [modified]

3-Dec-09 17:22

when i use mysql_use_result() then i am getting exception on line

field1=mysql_fetch_field(res1);

0xC0000005: Access violation reading location 0x00000040.

vasu_sri3-Dec-09 0:12

vasu_sri

3-Dec-09 0:12

i created one dialog based application. In that Dlg App class i am calling RegisterShellFileTypes(), in CWInApp::initInstace.

But application is crashing due to no poniter to document class.
code is like this :

CDesktopWallpaperDlg dlg;
m_pMainWnd = &dlg;

EnableShellOpen();
RegisterShellFileTypes();

INT_PTR nResponse = dlg.DoModal();
if (nResponse == IDOK)
{
    // TODO: Place code here to handle when the dialog is
    //  dismissed with OK
}
else if (nResponse == IDCANCEL)
{
    // TODO: Place code here to handle when the dialog is
    //  dismissed with Cancel
}

so, can anyone tell me what is the problem exactly?

it working with SDI Application..

Regards,
Srinivas

modified on Thursday, December 3, 2009 6:24 AM

Re: Getting problem with RegisterShellFileTypes() in MFC Dialog based application.

LunaticFringe3-Dec-09 0:23

LunaticFringe

3-Dec-09 0:23

The problem is precisely what the error message says. RegisterShellFileTypes creates registry entries to associate a document type and file extension with an .exe. If you aren't using the MFC DocView framework, there is no document class and the function call fails.

You can make the same registry entries manually; just because you aren't using the DocView framework doesn't mean you can't associate a file extension with an app, it just takes a bit more code.

Re: Getting problem with RegisterShellFileTypes() in MFC Dialog based application.

vasu_sri3-Dec-09 0:52

vasu_sri

3-Dec-09 0:52

when i call this RegisterShellFileTypes() in App Class,
internally in this function defination having pointer of document class.
but dlg based application doesn't have doc class. so that,

pointer is becoming NULL.

void CWinApp::RegisterShellFileTypes(BOOL bCompat)
{
	ASSERT(m_pDocManager != NULL);
	m_pDocManager->RegisterShellFileTypes(bCompat);
}

but,it is working fine with SDI Application.
i have tried in one sample SDI application.

Regards,
Srinivas

Re: Getting problem with RegisterShellFileTypes() in MFC Dialog based application.

LunaticFringe3-Dec-09 4:48

LunaticFringe

3-Dec-09 4:48

Yeah.... and what does SDI stand for? 'Single Document Interface'. It works in an SDI app because the SDI app has a document class, and fails in your dialog app because it doesn't have a document class.

Re: Getting problem with RegisterShellFileTypes() in MFC Dialog based application.

vasu_sri3-Dec-09 17:51

vasu_sri

3-Dec-09 17:51

I know what is the SDI stand for..

what iam asking that, how to do in dialog based.
i created one reg file. but
what should be write in reg file instead of document class does.

Regards,
Srinivas

Re: Getting problem with RegisterShellFileTypes() in MFC Dialog based application.

KingsGambit3-Dec-09 0:26

KingsGambit

3-Dec-09 0:26

It seems RegisterShellFileTypes() is to be used with SDI or MDI apps only.

unresolved external symbol "public: long __thiscall IWshRuntimeLibrary::IWshShortcut::Save(void)

includeh102-Dec-09 23:08

Re: unresolved external symbol "public: long __thiscall IWshRuntimeLibrary::IWshShortcut::Save(void)

2-Dec-09 23:08

what dll is relayed to the compile error?

Richard MacCutchan3-Dec-09 0:06

Richard MacCutchan

3-Dec-09 0:06

The one that's missing from your project, i.e maybe IWshRuntimeLibrary!

Re: unresolved external symbol "public: long __thiscall IWshRuntimeLibrary::IWshShortcut::Save(void)

includeh103-Dec-09 1:12

Re: unresolved external symbol "public: long __thiscall IWshRuntimeLibrary::IWshShortcut::Save(void)

3-Dec-09 1:12

IWshRuntimeLibrary works fine.

Richard MacCutchan3-Dec-09 1:31

Richard MacCutchan

3-Dec-09 1:31

includeh10 wrote:
IWshRuntimeLibrary works fine.

So are you saying that the title of this message "unresolved external symbol public: long __thiscall IWshRuntimeLibrary::IWshShortcut::Save(void)" has been fixed?

Re: unresolved external symbol "public: long __thiscall IWshRuntimeLibrary::IWshShortcut::Save(void)

includeh103-Dec-09 2:08