C / C++ / MFC Discussion Boards

Mike Dimmick13-Apr-05 8:16

13-Apr-05 8:16

The build utility for device drivers is called, appropriately enough, BUILD. This is the only supported way of building device drivers.

You can get Visual Studio/Visual C++ to invoke an external build procedure (i.e. run BUILD for you) by creating a Makefile project.

Stability. What an interesting concept. -- Chris Maunder

Re: How can I use the DDK with VC6.0?

Alexander ^M.,14-Apr-05 9:17

Alexander ^M.,

14-Apr-05 9:17

That is the usual way, but not the best one!
You can also use VS to build device drivers, but you have to set many linker settings and create some defines for it. Use google to find out the exact settings!

Don't try it, just do it! Wink | ;-)

Re: How can I use the DDK with VC6.0?

Mike Dimmick14-Apr-05 9:31

Mike Dimmick

14-Apr-05 9:31

I thought I'd linked to this article[^], but I hadn't.

From the comments:

"Using the procedure you outlined is BAD ENGINEERING PRACICE. It's precisely what we're trying to warn people about.

"If you use the process you describe, you've got the switches and settings right for ONE version of the DDK, and now you've got those switches and settings embedded in your VS project. What happens when a new DDK is released, and those switches CHANGE? Suppose the switches change (as they do) from build environment to build environment??

"No, dude, bad idea. THAT's why we describe this process."

Stability. What an interesting concept. -- Chris Maunder

Setting an event on minimize

Tom Wright13-Apr-05 4:22

Tom Wright

13-Apr-05 4:22

I have a dialog based application. I want to set an event when the user presses the minimize button, but when I try I get a message box that says cannot add new member. I'm writing this in VS6.0. Can anyone suggest something.

What I'm trying to do is minimize to the system tray. I'm using Chris Maunder's SystemTray class to do this. But it does not go to the system tray when minimized. The icon is in the system tray but I have to right click on it and choose hide to move it to the tray completly.

Thanks

Tom Wright
tawright915@yahoo.com

Re: Setting an event on minimize

Tom Wright13-Apr-05 4:49

Tom Wright

13-Apr-05 4:49

Never mind. I found it. I've got to look for the SC_MINIMIZE call in the OnSysCommand.

Thanks Tom...;P

Tom Wright
tawright915@yahoo.com

CTreeCtrl NM_CLICK notification.

Maximilien13-Apr-05 4:08

Maximilien

13-Apr-05 4:08

(either on VC6 and VC.net 2003 )

I have a ctreectrl on which I handle the NM_CLICK notification :

ON_NOTIFY( NM_CLICK,IDC_TREE, OnTreeClick )

and

void CMyClass::OnTreeClick( NMHDR* pNMHDR, LRESULT* pResult )
{
  NMTREEVIEW* pNMTreeView = (NMTREEVIEW*)pNMHDR;
  HTREEITEM  hSelItem = pNMTreeView->itemNew.hItem;
  /// ...
}

the item returned by pNMTreeView->itemNew.hItem is invalid when I click next to a tree item; it's not NULL and it's not a valid HTREEITEM.

Is it valid to use that or do I need to do something else ( like CTreeCtrl::GetSelectedItem ) ?

Thanks.

Max.

Maximilien Lincourt
Your Head A Splode - Strong Bad

Re: CTreeCtrl NM_CLICK notification.

Michael Dunn13-Apr-05 7:31

Michael Dunn

13-Apr-05 7:31

According to the docs, NM_CLICK for a tree doesn't send a NMTREEVIEW, just a plain NMHDR.

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

LINKS~! Ericahist | 1ClickPicGrabber | CP SearchBar v2.0.2 | C++ Forum FAQ
Strange things are afoot at the U+004B U+20DD

Pure Virtual Function Call

abc87613-Apr-05 3:57

abc876

13-Apr-05 3:57

I want to know when does "Pure Virtual Function Call" occurs? I am getting this problem in my code and unable to find out.

Note: I am not calling a pure vitual function in my base class constructor. So this error is not due to calling a pure virtual function from a base class constructor.

+
My application is a multithreaded application.

I wanna know the conceptual reasons behind other cases in which pure virtual function call can occur.

Thanks

Muhammad Shoaib Khan
http://geocities.com/lansolution

Re: Pure Virtual Function Call

digwizfox13-Apr-05 6:49

digwizfox

13-Apr-05 6:49

I have no idea what you are asking. Could you be more specific in describing your problem?

What do you mean, when does it occur? It occurs when someone types in the function call from another function and runs the program. Is there a compile error or weird runtime behavior that you are debugging?

Re: Pure Virtual Function Call

Anonymous13-Apr-05 6:59

Anonymous

13-Apr-05 6:59

The problem occurs on runtime.. a messagebox popups "Pure Virtual Function Call" and program terminates.

i have a base class which contain a pure virtual function. Another derived class provides its implementation. In my multithreaded application, when i try to call that function from base class pointer with address of derived class, this error occurs.. But it occurs in some rare scenario.. not consistant..

I just want to clarify the concept.. when does pure virtual function call occurs? in what possible scenarios can this runtime error occur

Re: Pure Virtual Function Call

digwizfox13-Apr-05 10:45

digwizfox

13-Apr-05 10:45

It's still kind of vague to me what you are doing. Normally, you call the virtual function using the base class pointer. I don't see any reason why having a derived class pointer would cause a problem. But as a design critique, the purpose of virtual functions is to be able to hide dependencies by using the base class pointer to interface to the object. That way, the users of the object are only bound to the base class at compile time. During runtime, the user is unaware that the derived class actually implements the function. There isn't much point in creating a pure virtual function if the users of your object are calling the function from a derived class pointer anyway. That defeats the purpose of run time binding.

You should have some kind of factory build the classes so that the dependency on the derived class is controlled and limited. The actual users of the class that call the functions should get pointers of the base class type from the factory. Then if the implementation needs changed in the future, not as many pieces of your program have to recompile when you make changes.

Maybe you could show us your class declarations and a few code snippets where the function calls are made to give us an example of what you are doing.

Re: Pure Virtual Function Call

Mike Dimmick13-Apr-05 8:37

Mike Dimmick

13-Apr-05 8:37

Most likely you are, indirectly, calling a pure virtual function in your base class constructor.

I recently wrote up how the compiler handles abstract classes and the C++ rules for which overrides are called at what point in answer to a question here[^].

Basically what's happening is you're trying to call through a virtual function that was declared pure either in your class or one of your base classes.

One possibility:

// In some header
 
class A
{
public:
   A();
 
protected:
   void OtherFunc();
 
   virtual void MyFunc() = 0;
};
 
class B : public A
{
public:
   B();
 
   virtual void MyFunc();
};
 
// Source file a1.cpp
 
A::A()
{
   OtherFunc();
}
 
void A::OtherFunc()
{
   MyFunc();
}
 
B::B()
{
}
 
void B::MyFunc()
{
}

When A's constructor body runs, the virtual function pointer is still pointing to A's vtable. The constructor calls OtherFunc which calls MyFunc, which is generated as a virtual call through the vtable. However, A::MyFunc is a pure virtual function; calling it this way is an error. The Visual C++ compiler traps the error by making the vtable slot point to a routine in the runtime library which reports the error.

Stability. What an interesting concept. -- Chris Maunder

Re: Pure Virtual Function Call

Anonymous13-Apr-05 8:49

Anonymous

13-Apr-05 8:49

No , i have already mentioned. i am not calling it through constructor.
Any other reason?

anyways, thanks
Shoaib

Re: Pure Virtual Function Call

mark novak14-Apr-05 0:38

mark novak

14-Apr-05 0:38

I've never experienced a pure virtual function call. However from what I hear it really can only happen in the constructor or in the deconstructor. Then off course it could be a side effect of using invalid pointers to these objects. Also MSVC6 has been known to allow abstract classes to be created in certain cases. It also never hurts to do a rebuild all. I’ve seen some really straight up weird occurrences cause me a good couple hours of confusion all completely melt with a simple rebuild all.

Service Control Manager types with MFC

sweep12313-Apr-05 3:41

sweep123

13-Apr-05 3:41

I have been trying to use the http://www.beyondlogic.org/porttalk/porttalk.htm[^]">PortTalk device driver to access the parallel ports of my PC.

The sample Console applications works OK, but when I try and use this code in a MFC application I get the following errors:-

c:\ParallelPortTest\ParallelPortTest\pt_ioctl.c(114): error C2065: 'SC_HANDLE' : undeclared identifier
c:\ParallelPortTest\ParallelPortTest\pt_ioctl.c(114): error C2146: syntax error : missing ';' before identifier 'SchSCManager'
c:\ParallelPortTest\ParallelPortTest\pt_ioctl.c(114): error C2065: 'SchSCManager' : undeclared identifier

I have tried many complier options but still get the above errors, any suggestions?

Re: Service Control Manager types with MFC

Alexander ^M.,13-Apr-05 3:55

Alexander ^M.,

13-Apr-05 3:55

Check the include files and the defines (maybe version conflict, MFC assumes windows NT 4.0 -> stdafx.h ).

Don't try it, just do it! Wink | ;-)

Re: Service Control Manager types with MFC

sweep12313-Apr-05 4:10

sweep123

13-Apr-05 4:10

Running Windows 2000 SP3 and have included stdafx.h, still lots of errors.

Re: Service Control Manager types with MFC

Ravi Bhavnani13-Apr-05 5:30

Ravi Bhavnani

13-Apr-05 5:30

Is winsvc.h being #included?

/ravi

My new year's resolution: 2048 x 1536
Home | Articles | Freeware | Music
ravib@ravib.com

Re: Service Control Manager types with MFC

sweep12313-Apr-05 5:38

sweep123

13-Apr-05 5:38

Thanks, I included #include winsvc.h in the file that was giving the errors.

BUT now get the following Link Erros:-

ParallelPortTest error LNK2005: "void __cdecl outportb(unsigned short,unsigned char)" (?outportb@@YAXGE@Z) already defined in ParallelPortTest.obj
ParallelPortTest error LNK2005: "unsigned char __cdecl inportb(unsigned short)" (?inportb@@YAEG@Z) already defined in ParallelPortTest.obj
ParallelPortTest error LNK2005: "unsigned char __cdecl OpenPortTalk(void)" (?OpenPortTalk@@YAEXZ) already defined in ParallelPortTest.obj
ParallelPortTest error LNK2005: "void __cdecl ClosePortTalk(void)" (?ClosePortTalk@@YAXXZ) already defined in ParallelPortTest.obj

Do you know what libraries to include?

problem with functions and variables...

Green Fuze13-Apr-05 2:35

Green Fuze

13-Apr-05 2:35

Hey everybody! Smile | :)

I created 2 function.

<br />
void CHelperDlg::UpdateVars(void) //updates the vars in the options<br />
{<br />
  CFile fLinkAfter(m_strAppPath+"\\Settings\\LinkAfter.dat", CFile::modeReadWrite);<br />
<br />
  ReadFiles(m_clsOptions.m_OptionLinkAfter, fLinkAfter);<br />
	MessageBox(m_clsOptions.m_strOptionLinkAfter);<br />
}<br />
<br />
void CHelperDlg::ReadFiles(CString TheVar, CFile ReadedFile)<br />
{<br />
	char cBuffer[10];<br />
	UINT iRead;<br />
<br />
	iRead = ReadedFile.Read(cBuffer, 10);<br />
	TheVar = cBuf;<br />
}<br />

now, as far as I understand the var "m_clsOptions.m_OptionLinkAfter"
should get the content of the cBuf, and for some reason, the
"m_clsOptions.m_OptionLinkAfter" still remains empty after the other function is called (checked with the MessageBox).
(TheVar gets m_clsOptions.m_strOptionLinkAfter as its parameter)

shouldn't the ReadFiles function update m_clsOptions.m_strOptionLinkAfter???

THANKS!!!

Re: problem with functions and variables...

David Crow13-Apr-05 2:41

David Crow

13-Apr-05 2:41

Green Fuze wrote:
void CHelperDlg::ReadFiles(CString TheVar, CFile ReadedFile)

Change to:

void CHelperDlg::ReadFiles(CString &TheVar, CFile ReadedFile)

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

Re: problem with functions and variables...

Green Fuze13-Apr-05 13:28

Green Fuze

13-Apr-05 13:28

Perfect!

and I think I just understood something really important!

thanks!

Re: problem with functions and variables...

Ryan Binns13-Apr-05 18:28

Ryan Binns

13-Apr-05 18:28

On top of that, make sure you pass your CFile object by reference or pointer, otherwise the state of the CFile object when returning from the function will be out of sync with the state of the operating system file handle.

Ryan

"Punctuality is only a virtue for those who aren't smart enough to think of good excuses for being late" John Nichol "Point Of Impact"

encrypt to database in vc++

nehathoma13-Apr-05 1:52

nehathoma

13-Apr-05 1:52

Do anyone know how to encrypt a data into a database in vc++?plz help me!!!

Re: encrypt to database in vc++

Yulianto.13-Apr-05 15:02

Yulianto.

13-Apr-05 15:02

What do you want to know? The encrypt method, or the encripting with vc++? You can google and find encrypt method.

<italic>Work hard, Work effectively and a bit of luck is the key to success.

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.