Q113534: FIX: C2248 Error When Calling CView::OnInitialUpdate()

Article: Q113534
Product(s): Microsoft C Compiler
Version(s): winnt:1.0
Operating System(s): 
Keyword(s): kbDocView kbMFC kbVC100bug kbVC150fix kbGrpDSMFCATLkbbuglist kbfixlist
Last Modified: 07-MAY-2001

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The information in this article applies to:

- The Microsoft Foundation Classes (MFC), used with:
   - Microsoft Visual C++ for Windows, 16-bit edition, version 1.0 
   - Microsoft Visual C++, 32-bit Editions, version 1.0 
-------------------------------------------------------------------------------

SYMPTOMS
========

Attempting to call CView::OnInitialUpdate() from a non-CView derived class
causes the compiler to generate the following error message:

  

  error C2248: 'OnInitialUpdate' : cannot access protected member
  declared in class 'CView'

CAUSE
=====

The CView class contains the function OnInitialUpdate(), which is called by the
framework after the view is attached to a document but before the view is
initially displayed. OnInitialUpdate() is declared as a protected member of the
CView class. Protected member functions cannot be accessed by objects of another
class type unless that class is derived from the protected member function's
class or is declared to be a friend of the protected member function's class.

RESOLUTION
==========

To work around this problem, do one of the following:

- Upgrade to Visual C++ version 1.5. MFC version 2.5 supplied with Visual C++
  version 1.5 for Windows declares the OnInitialUpdate() function as a public
  member of the CView class.

-or-

- Use the CWnd::SendMessage function to send a WM_INITIALUPDATE message to the
  view. For example:

        class CAnotherClass
        {
            void MemberFunction()
            {
                CDerivedView * pView = new CDerivedView;

                if( pView != NULL )
                    pView->SendMessage(WM_INITIALUPDATE);
            }
        };

-or-

- Derive from CView and declare the class where OnInitialUpdate() is being
  called from as a friend. For example:

        class CDerivedView : public CView
        {
            friend class CAnotherClass;

         public:
             virtual void OnDraw(CDC* pDC);
         };

-or-

- Derive from CView and override the OnInitialUpdate() member function, making
  the override a public member of the derived class. For example:

        class CDerivedView : public CView
        {
        public:
            virtual void OnDraw(CDC* pDC);
            virtual void OnInitialUpdate(){ CView::OnInitialUpdate(); }
        };

STATUS
======

Microsoft has confirmed this to be a problem in the Microsoft Foundation Classes
(MFC) version 2.0. The problem was corrected in MFC version 2.5 and MFC version
3.0.

Additional query words: 1.00 2.00 2.10 CScrollView CFormView

======================================================================
Keywords          : kbDocView kbMFC kbVC100bug kbVC150fix kbGrpDSMFCATL kbbuglist kbfixlist
Technology        : kbAudDeveloper kbMFC
Version           : winnt:1.0
Issue type        : kbbug
Solution Type     : kbfix

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