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->((CMainFrame*): syntax error : '(' ; why?

Posted on 1998-01-14
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Last Modified: 2010-04-10
I have some errors that I cannot resolve. I'm using VC++ 4.0, DirectX 3.0.

This line:

AfxGetApp()->m_pMainWnd->m_pDirectDraw->GetDisplayMode(&ddsdDesc);

Gives the following error:

Compiling...
MainFrm.cpp
C:\Vc++\Projects\Asteroid\MainFrm.cpp(579) : error C2039: 'm_pDirectDraw' : is not a member of 'CWnd'

m_pDirectDraw, true enough, is not a member of CWnd. It's a member of class CMainFrame (: public CFrameWnd). That's why I need to cast it to CMainFrame, right? So, I tried:

AfxGetApp()->((CMainFrame*)m_pMainWnd)->m_pDirectDraw->GetDisplayMode(&ddsdDesc);

And received this:

Compiling...
MainFrm.cpp
C:\Vc++\Projects\Asteroid\MainFrm.cpp(579) : error C2059: syntax error : '('

What's wrong with a "(" there? I have to cast it. To cast something, you need to enclose the new type in (), right?

How do I fix this?
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Question by:TylerRick
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4 Comments
 
LVL 22

Expert Comment

by:nietod
ID: 1178315
Try
     (CMainFrame*)(AfxGetApp()->m_pMainWnd)->m_pDirectDraw->GetDisplayMode
0
 
LVL 15

Accepted Solution

by:
Tommy Hui earned 200 total points
ID: 1178316
More correctly, you should use MFC's runtime type info:

  CMainFrame* frame = NULL;
  if (AfxGetApp()->m_pMainWnd->IsKindOf(RUNTIME_CLASS(CMainFrame)))
  {
    frame = (CMainFrame*)AfxGetApp()->m_pMainWnd;
    frame->m_pDirectDraw->GetDisplayMode(&ddsdDesc);
  }
  else
  {
    TRACE("Pointer is not the right type!\r\n");
  }

0
 

Author Comment

by:TylerRick
ID: 1178317
Thanks! Both of your suggestions worked.

To nietod:

I had to change your example to:
((CMainFrame*)(AfxGetApp()->m_pMainWnd))->m_pDirectDraw->GetDisplayMode(&ddsdDesc);
0
 

Author Comment

by:TylerRick
ID: 1178318
Thanks! Both of your suggestions worked.

To nietod:

I had to change your example to:

((CMainFrame*)(AfxGetApp()->m_pMainWnd))->m_pDirectDraw->GetDisplayMode(&ddsdDesc);

before it compiled, though.
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