Re: C++ operator - C / C++ / MFC Discussion Boards

Fred/M11-Dec-01 3:22

11-Dec-01 3:22

Hi, everybody, i need some help for writing an operator=

:::::::::::::::::::::::::::::::

class aa
{
public:
int var;
virtual aa& operator=(const aa && c ) throw();
};

:::::::::::::::::::::::::::::::
class bb : public aa {
public:
int varbb;

bb& operator=(const bb && c )
{
varbb=c.varbb;
return *this;
};
};

int main()
{
aa * xx = new bb();
aa * yy = new bb();

*xx=*yy;
};
Problem:

Ok, so when i execute this code "*xx=*yy" the aa operator= was called, but i want to use the bb operator=.
How can i do that?

Ho, sorry for my english.

Re: C++ operator

Ernest Laurentin11-Dec-01 4:08

Ernest Laurentin

11-Dec-01 4:08

In that case you must declare the operator in class bb the same way than
in class aa. Did you notice that they are not compatible?
They both must be virtual. (In fact, that's the first time I saw someone
using virtual operator but hey, it's good to know. Thanks).

Re: C++ operator

Alvaro Mendez11-Dec-01 4:15

Alvaro Mendez

11-Dec-01 4:15

Since the bb operator is not declared exactly as the aa operator, they're not treated polymorphically. In other words, they appear as two different functions and the compiler uses the one that most closely matches.

Regards,
Alvaro

Re: C++ operator

Fred/M11-Dec-01 4:42

Fred/M

11-Dec-01 4:42

Ok , thank's a lot Smile | :)

But do you know the solution for my problem.

Re: C++ operator

Alvaro Mendez11-Dec-01 5:42

Alvaro Mendez

11-Dec-01 5:42

The solution is to add another assignment operator inside bb that looks exactly like the one in aa. Then you can call bb operator from there by casting the parameter to bb&:

virtual aa& operator=(const aa& c) throw()
{
   return operator=((bb&)c);
}

Regards,
Alvaro

Re: C++ operator

Jonathan Gilligan11-Dec-01 4:55

Jonathan Gilligan

11-Dec-01 4:55

* reinterpret_cast<bb *>(xx) = * reinterpret_cast<bb *>(yy);

Bomb our homes and threaten our children, and, as difficult as it is, we will still love you --- Martin Luther King, Jr.

Re: C++ operator

Fred/M11-Dec-01 5:18

Fred/M

11-Dec-01 5:18

Thank's, but sometimes i don't know the real type of xx and yy, and i dont want to know.
I don't write this code with a switch.
Other idea ?

Re: C++ operator

Michael Dunn11-Dec-01 8:00

Michael Dunn

11-Dec-01 8:00

Can operators even be virtual? You certainly can't make = virtual, because = always operates on a object, not a pointer to an object, as is required for polymorphism.

--Mike--
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Unicode/MBCS compatibility

DataPrasad11-Dec-01 3:18

DataPrasad

11-Dec-01 3:18

Hello experts,

Well,I have a VC++ 6.0 developed application, supporting MBCS, which is the default for VC++ 6.0. Also, let me tell you I am using Windows 2000 platform.

Then, I have compiled it with UNICODE MFC dlls and static librarys[ UAFX*.lib and Unicode MFC dlls] and got the UNICODE version of application.

Now, my requirement is to develop one single application that can support both Unicode and MBCS[DBCS]....

Well, I dont know wehether this is possible, if Possible, please let me know how to go for.

Thanks & Regards,
Mr Prasad G.

Re: Unicode/MBCS compatibility

PJ Arends11-Dec-01 9:20

PJ Arends

11-Dec-01 9:20

While I'm not an expert, I will try to answer your question.

Use the TCHAR macro's for all your string manipulations (CString does this)

ie.
use 'TCHAR' instead of 'char' or 'WCHAR'
use '_tcscpy' instead of 'strcpy', '_mbscpy', or 'wcscpy'

HTH

---
It may be that your sole purpose in life is simply to serve as a warning to others.

snapshot and dynamic recordset!

mazy11-Dec-01 2:59

mazy

11-Dec-01 2:59

I wrote database program,and my m_pSet(recordset) is snapshot and I can use AddNew() function;when I change m_nDefaultType to dynaset I can't use AddNew() and when I use CanAppend() it does not append!
How can I add a new record to dynaset record?

thanks

Re: snapshot and dynamic recordset!

Carlos Antollini11-Dec-01 3:10

Carlos Antollini

11-Dec-01 3:10

You only can set the type of recordset in the openrecordset. Is for this that the only way is close the recordset an open again, using a dynaset type...

Cheers!!! Smile | :)

Carlos Antollini.
Sonork ID 100.10529 cantollini

beginner question : DocView

Jerome Conus11-Dec-01 2:57

Jerome Conus

11-Dec-01 2:57

Hi !

I have an app using the Doc-View architecture.

In my View class, I have a method GetDocument().
I would like to be able to access the document from my mainApp class, not from the view. GetDocument() is using the member property m_pDocument, but I cannot use it from my mainApp class. How can I get a pointer to my CDocument class from my App class ?

Thanks for your help !

Jerome

Re: beginner question : DocView

Michael Dunn11-Dec-01 8:02

Michael Dunn

11-Dec-01 8:02

AfxGetMainWnd()->GetActiveView()->GetDocument()

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XP Buttons and Dropdowns

11-Dec-01 2:33

Hello!

How do I get those nice blue/white buttons and dropdown menus that most XP applications use in my MFC app?

Hollow in MFC. Please help.

The_Server11-Dec-01 1:39

The_Server

11-Dec-01 1:39

Hi, All !!!
=======

Last time I asked: How to grayscale a picture, and didn't got an answer.

Well...
If you guys wanna know how, there is your answer:
I found out that in order to have a gray color,
all Red,Green & Blue must have the same value.
So...

<code>void</code> GrayscaleIt(MyPicture & pic)
{
  for (<code>int</code> y=0; y<pic.height; y++)
    for (<code>int</code> x=0; x<pic.width; x++)
    {
      <code>COLORREF</code> col= pic.GetPixel(x,y);
      <code>unsigned char</code> gs= ((GetRValue(col)+GetGValue(col)+GetBValue(col))/3);
      pic.SetPixel(x,y, RGB(gs,gs,gs));
    }
}

BTW:

I have a question.

After the win32 AppWizard, In order to make my window "transparent" or "hollow",
I need to change the wcex.hbrBackground to 0;
Like this:

ATOM MyRegisterClass(HINSTANCE hInstance)
{
  WNDCLASSEX wcex;

  wcex.cbSize = sizeof(WNDCLASSEX); 

  wcex.style		= 0;//CS_HREDRAW | CS_VREDRAW;
  wcex.lpfnWndProc	= (WNDPROC)WndProc;
  wcex.cbClsExtra	= 0;
  wcex.cbWndExtra	= 0;
  wcex.hInstance	= hInstance;
  wcex.hIcon		= LoadIcon(hInstance, (LPCTSTR)IDI_GRAY1);
  wcex.hCursor		= LoadCursor(NULL, IDC_ARROW);
<code>  wcex.hbrBackground	= NULL;//(HBRUSH)(COLOR_WINDOW+1);</code>
  wcex.lpszMenuName	= NULL;//(LPCSTR)IDC_GRAY1;
  wcex.lpszClassName	= szWindowClass;
  wcex.hIconSm		= LoadIcon(wcex.hInstance, (LPCTSTR)IDI_SMALL);

  return RegisterClassEx(&wcex);
}

How do I do it in MFC ????? Cry | :((

Please, HELP!

BTW: come to #CodeProject on DalNet (mIRC)

Re: Hollow in MFC. Please help.

Alvaro Mendez11-Dec-01 4:19

Alvaro Mendez

11-Dec-01 4:19

Take a look at PreCreateWindow, which you can override in your CMainFrame class.

Regards,
Alvaro

Re: Hollow in MFC. Please help.

Michael Dunn11-Dec-01 8:04

Michael Dunn

11-Dec-01 8:04

Call AfxRegisterWndClass() and save the returned string. Use that string as your window class name.

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Using standard ActiveX (VC++ 6.0)

DABMSC10-Dec-01 23:55

DABMSC

10-Dec-01 23:55

(Visual C++6.0 on OS w2k)
I have the following problem using standard microsoft ActiveX MSComm32 or others:
when I create this object and I run my application in
debug mode there is always a COleException raised:

Warning:_ constructing COleException,
scode=DIPS_E_MEMBERNOTFOUND ($80020003).

I create the object as below:
CString csLicKey = "Copyright (c) 1994 ";
BSTR bstrLicKey = csLicKey.AllocSysString();

if(!m_CommCtrl.Create("Communications Control",
WS_CHILD, CRect(0,0,40,40), this, IDC_COMMCTRL, NULL,
FALSE, bstrLicKey))

I couldn't trap this exception. And I couldn't discover
why it was raised.
Someone knows something about this issue?

Re: Using standard ActiveX (VC++ 6.0)

Michael P Butler11-Dec-01 0:21

Michael P Butler

11-Dec-01 0:21

Assuming you mean DISP_E_MEMBERNOTFOUND and not DIPS_E_MEMBERNOTFOUND.

MSDN states the following,

Debugging Output You Can Safely Ignore
When you're debugging a control, you may get a series of messages in Visual C++'s debugging window. Although it's not documented anywhere, some of these messages can be safely ignored. For instance, when I debug the StopLite control in the test container using Visual C++ version 4.2, I get the following:

Loaded symbols for 'C:\WINNT35\system32\MFC42.DLL'
LDR: WARNING ! MAJOR PERFORMANCE LOSS in TSTCON32.EXE
LDR: Dll MFC42D.DLL base 5f400000 relocated due to collision with
C:\WINNT35\System32\MFC42.DLL
Loaded symbols for 'C:\WINNT35\system32\MFC42D.DLL'
Loaded symbols for 'C:\WINNT35\system32\MSVCRTD.DLL'
Loaded symbols for 'C:\WINNT35\system32\MFCO42D.DLL'
Warning: constructing COleException, scode = DISP_E_MEMBERNOTFOUND ($80020003).
First-chance exception in TSTCON32.EXE (MFCO42D.DLL): 0xE06D7363: Microsoft C++ Exception.

The first line is just notification that the debugging symbols for the release version MFC DLL were loaded when the test container, which uses the release version of the MFC DLL, was loaded.

The second and third lines (which begin with "LDR:") warn that the debugging version of the MFC DLL (used by the StopLite control) had to be relocated in my address space because it conflicted with the release version of the same DLL (which is being used by the test container). Although this means that it took a little longer to load the MFC DLL, it isn't a big deal because it only happens when you're debugging in the test container. You can ignore these messages. (Since Visual Basic apps don't use the MFC DLL at all, you won't get this message if you use a Visual Basic app as your test container.)

The next three lines are notifications that debugging symbols have been loaded.

The last two lines are notification that an exception has been thrown because the test container didn't provide a Color property to be read. This is okay, because we've provided a default value for the property. You won't get this error if you use a container that provides the property, such as a Visual Basic application.

In Visual C++ version 4.1, the only line I got was a warning about the exception for properties that couldn't be loaded from the container.

First-chance exception in TSTCON32.EXE (MFC40.DLL): 0xE06D7363: Microsoft C++ Exception.

Depending on how your container handles threads, you may also get occasional messages about threads exiting. You don't need to worry about these, either.

Michael Smile | :)

How do I change the page layout (page orientation) during printing?

Youknowme10-Dec-01 23:14

Youknowme

10-Dec-01 23:14

thanks,

Tien,

Re: How do I change the page layout (page orientation) during printing?

Bernhard10-Dec-01 23:59

Bernhard

10-Dec-01 23:59

how do you print ? with the doc / view architecture or somehow different ?

OnPrepareDC (CDC* pDC, CPrintInfo* pInfo)
{
..
DEVMODE* pDevMOde = pInfo->m_pPD->GetDevMode();
pDevMode->dmOrientation = DMORIENT_LANDSCAPE; //DMORIENT_PORTRAIT
pDC->ResetDC (pDevMode);
}

This would be the approach for the doc / view arch. if you use another way, post the code...

hope this helps..
bernhard

"There are three roads to ruin: women, gambling and technicians. The most pleasant is with women, the quickest is with gambling, but the surest is with technicians." Georges Pompidou

Stupid question answered thousand times

Krouer10-Dec-01 22:51

Krouer

10-Dec-01 22:51

I'm an experimented developper (I believe I am) but I'm a bit lost.
I want to create a Internet Explorer PlugIn but when I open the new project dialog, I don't know what to choose. It's very embarrasing Confused | :confused:

.

FYI, I want to put some buttons and a listbox.
How can I force the user to install it when he opens the page?

Can I create a Dialog application with automation server? Does that work?

Re: Stupid question answered thousand times

moliate11-Dec-01 2:09

moliate

11-Dec-01 2:09

There are some different approaches. Do you want to add the controls to the browser (BHO) or to the document (ActiveX)? An article on BHO:s can be found here:

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnwebgen/html/bho.asp

If you want the controls in the document, try an ActiveX Document Server.

/moliate

'Pushing' a thread...

Mr.Freeze10-Dec-01 22:38

Mr.Freeze

10-Dec-01 22:38

Hi,

I'm wondering if it is possible to 'push' a thread to execute more often when another thread is waiting for some data from the first one?

The concret case is the following: My application created a secondary thread for displaying data. The main thread modifies that data and to avoid displaying wrong data I use flags.
When the secondary thread is busy, the first one waits until the security flag is reset. Depending on the compiler options the results are different: for 'standard optimization' there is no problem, but for 'speed optimized' the main thread waits forever because somehow the secondary thread doesn't continue... ??
Can someone help ??

Thanks Smile | :)

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