assigning string value to CDBVariant - C / C++ / MFC Discussion Boards

Re: memory leak in ADO Connection & Excute methods

Roger Stoltz5-Feb-07 23:17

5-Feb-07 23:17

John Simmons / outlaw programmer wrote:
Of course, I'd also like to add that he should consider other employment opportunities after that kind of question...

"It's supposed to be hard, otherwise anybody could do it!" - selfquote

Exception in VC++ Code.

T.RATHA KRISHNAN5-Feb-07 21:27

T.RATHA KRISHNAN

5-Feb-07 21:27

I have created a Visual Studio.NET 2003 project using MFC. It's a gaming project. If I execute this project a window opens. After completing all the gaming operations,if I close the window, an exception occurs stating that

'Unhandled exception at 0x7c918fea in Perspective.exe: 0xC0000005: Access violation writing location 0x00000010.'

This exception occurs under both Debug and Release modes.

When I break this exception, it goes to a class free.c which is not created by me.

How to resolve this exception?

Re: Exception in VC++ Code.

prasad_som5-Feb-07 21:31

prasad_som

5-Feb-07 21:31

As error says, its due to access violation. And that is due to your code.
Can you post relevent code ?

Prasad
Notifier using ATL | Operator new[],delete[][^]

Re: Exception in VC++ Code.

kakan5-Feb-07 21:35

kakan

5-Feb-07 21:35

Follow the call stack until you find a function that you wrote. And there you will find the cause of the problem.

Alcohol. The cause of, and the solution to, all of life's problems - Homer Simpson

Re: Exception in VC++ Code.

Michael Dunn5-Feb-07 22:36

Michael Dunn

5-Feb-07 22:36

When you get a crash when accessing location 0 or something near 0, it means you're dereferencing a null pointer.

--Mike--
Visual C++ MVP Cool | :cool:

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Re: Exception in VC++ Code.

Hamid_RT6-Feb-07 0:11

Hamid_RT

6-Feb-07 0:11

I think your problem is of pointers.

WhiteSky

Re: Exception in VC++ Code.

ThatsAlok6-Feb-07 19:55

ThatsAlok

6-Feb-07 19:55

T.RATHA KRISHNAN wrote:
Unhandled exception at 0x7c918fea in Perspective.exe: 0xC0000005: Access violation writing location 0x00000010.'

you tried to called something on NULL pointer without providing it memory

"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow

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Alok Gupta
VC Forum Q&A :- I/ IV
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assigning string value to CDBVariant

prithaa5-Feb-07 21:23

prithaa

5-Feb-07 21:23

Hello,

How do I assign a value to an object of type CDBVariant?Especially if the data type is string.

CDBVariant b;
CString str;
b.m_dwtype = DBVT_STRING;
b.m_pstring = str;

but in the union of CDBVariant m_pstring is pointer to string.so what has to be done?

Thanks
Pritha

Re: assigning string value to CDBVariant

prasad_som5-Feb-07 22:52

prasad_som

5-Feb-07 22:52

prithaa wrote:
b.m_pstring = str

Pass address of string.

CDBVariant b;
CString str;
b.m_dwtype = DBVT_STRING;
b.m_pstring = &str;

Prasad
Notifier using ATL | Operator new[],delete[][^]

Re: assigning string value to CDBVariant

prithaa5-Feb-07 23:44

prithaa

5-Feb-07 23:44

Hello,

So I need to maintain the CString variable so that the pointer has a meaning .I cannot destroy the the CString object or create the object locally ? i.e

Thanks for your reply Prasad
Prithaa

Re: assigning string value to CDBVariant

prasad_som6-Feb-07 0:33

prasad_som

6-Feb-07 0:33

True.

Prasad
Notifier using ATL | Operator new[],delete[][^]

Re: assigning string value to CDBVariant

Naveen6-Feb-07 0:49

Naveen

6-Feb-07 0:49

prithaa wrote:
b.m_pstring = str;

instead use

b.m_pstring = new CString(str);

the destructor of the CDBVariant will delete this newly created CString.

nave

Convert DWG/BMP image file to PNG image format

helpcode5-Feb-07 20:39

helpcode

5-Feb-07 20:39

Hi,
I am developing a application in which i need to convert the .DWG/.BMP image files into PNG image file format. Can anybody help me to this in VC++ ?
Thanks in Advance !!

Jiteen

Re: Convert DWG/BMP image file to PNG image format

Hamid_RT5-Feb-07 20:54

Hamid_RT

5-Feb-07 20:54

See http://www.wotsit.org[^] for info about graphic files.If you want to save file you can read bmp or png(not dwg)file with CImage class and use of CImage::Save but for dwg I think you need to lot of work.;)

WhiteSky

Re: Convert DWG/BMP image file to PNG image format

helpcode6-Feb-07 0:33

helpcode

6-Feb-07 0:33

Thanks a lot sir !!

Jiteen

Re: Convert DWG/BMP image file to PNG image format

Hamid_RT6-Feb-07 0:51

Hamid_RT

6-Feb-07 0:51

You're welcome Wink | ;)

WhiteSky

how to add check boxes

pavan_sw5-Feb-07 20:11

pavan_sw

5-Feb-07 20:11

how to add checkboxs for multiple coloumns in listview..
LVS_EX_CHECKBOXES is working for only one coloumn.......

Re: how to add check boxes

Hamid_RT5-Feb-07 20:28

Hamid_RT

5-Feb-07 20:28

See Adding Checkboxes to a list control[^] and XListCtrl - A custom-draw list control with subitem formatting [^]

WhiteSky

Re: how to add check boxes

ThatsAlok6-Feb-07 19:55

ThatsAlok

6-Feb-07 19:55

pavan_sw wrote:
how to add checkboxs for multiple coloumns in listview..
LVS_EX_CHECKBOXES is working for only one coloumn...

CLIstCtrl::ModifyStyleEx

"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow

cheers,
Alok Gupta
VC Forum Q&A :- I/ IV
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Message Map Return types

G.DHANASEKAR5-Feb-07 19:18

G.DHANASEKAR

5-Feb-07 19:18

How to make ON_ENCHANGE message Map returning an int or CSize?

I have added this in the header file:
afx_msg int OnEnChangeEditmessage();

The message map I added was :
ON_EN_CHANGE(IDC_EDITMESSAGE, _OnEnChangeEditmessage)

My message handling function is:

int CPreferences::OnEnChangeEditmessage()
{
CPaintDC *pDC;
CSize size;

size = pDC->GetTextExtent(m_strMessage);
return size.cx;
}

ikikhjkhjkhjkhj

Re: Message Map Return types

Don Box5-Feb-07 19:46

Don Box

5-Feb-07 19:46

Typecast OnEnChangeEditmessage in ON_EN_CHANGE(IDC_EDITMESSAGE, OnEnChangeEditmessage) to the original prototype.

Come online at:-
jubinc@skype

Re: Message Map Return types

Roger Stoltz5-Feb-07 22:58

Roger Stoltz

5-Feb-07 22:58

Stop! Wrong way.

All message handlers that are put inside the message map have specific declarations.
In your case the prototype shall look like this, the identifier name excepted:

afx_msg void OnEnChangeEditMessage();

You cannot change the return type for message handlers. You have to solve whatever problem you're having in another way. All message handlers in Win32 always return an LRESULT. In MFC this is hidden so MFC message handlers for windows returns void, like above. But if you write a message handler for a user defined message you still have to return an LRESULT, even when using MFC.

Describe your problem if you want suggestions for alternative solutions.

"It's supposed to be hard, otherwise anybody could do it!" - selfquote

Re: Message Map Return types

Mark Salsbery6-Feb-07 8:08

Mark Salsbery

6-Feb-07 8:08

Going a layer further than Roger's reply - take a look at the EN_CHANGE notification docs.
There is no return value. Even if you returned something it would be ignored by the system.
The platform sdk is your friend Smile | :)

Re: Message Map Return types

ThatsAlok6-Feb-07 19:56

ThatsAlok

6-Feb-07 19:56

wrote:
My message handling function is:

int CPreferences::OnEnChangeEditmessage()
{
CPaintDC *pDC;
CSize size;

size = pDC->GetTextExtent(m_strMessage);
return size.cx;
}

every Message map has it specific handler... you have to consult MSDN for same

"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow

cheers,
Alok Gupta
VC Forum Q&A :- I/ IV
Support CRY- Child Relief and you

Set Edit Box Text from Different Dialog

Sonani Prakash5-Feb-07 19:08

Sonani Prakash

5-Feb-07 19:08

There are two seperate application dialog.
on one dialog there is one text box as well as check box and on other dialog
there is one button.

now if I press on second dialog's button,then some text should be set on
first dialog's text box and checkbox.

I am able to set text of checkbox but not able to set text into edit box.
I used logic like following
CWnd* pWnd = CWnd::FindWindow(NULL,_T("TestDialog"));
if (pWnd)
{
pWnd->ShowWindow(SW_SHOW);
pWnd->SetForegroundWindow();
pWnd->SetDlgItemText(1003,"Hello");
pWnd->SetDlgItemText(1001,"Hello111");

}

Can anybody tell me how to set text on other application dialog's edit box

Thanks,
Prakash

sonani prakash

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