Error assigning values?!!

[raner]

Hi A very unexpected error happened...below is the code snippet.

CMy3027View *pView;
CMainFrame *pMF = (CMainFrame*)AfxGetMainWnd();
pView = (CMy3027View*)pMF->GetActiveView();

m_numOfValues= pView->m_imageIndex;

where m_numOfValues is declared as a class member variable(integer), m_imageIndex is a public member variable of my CView class. 1. On debugging,pView->m_imageIndex is working fine but m_numOfValues just doesnt get assigned. It even ran into exception error. 2. In a previous version of the same program, the same method of assignment had work fine. I have no idea why it's not working suddenly. 3. When i try declaring m_numOfValues locally(in the function) instead, the assignment work fine. 4.Another problem is i declared

CMy3027View *pView;

in my class's header file, under private.But after assigning it in a member function, the subsequent functions do not see the assigned value. Anyone has any idea wat's happening? pls help.. thks

[AlexO]

In relese that assigment might be optimized, so it is not surprizing you do not see it. As for the exception the code below might show you the problem raner wrote:_

pView = (CMy3027View*)pMF->GetActiveView();

if(0 == pView)

MsgBox("This is  the problem");

_

[Joao Paulo Figueira]

Downcasts are always unsafe. Are you sure that the CView* returned by GetActiveView() is a CMy3027View*? If it's not, the program may bomb...

[raner]

oh yah, i do get the "This is the problem" message box..but what does it mean?;P

[raner]

i don't know how to see that the returned pointer is a CMy3027View*..but i've only one CView-derived class so i thought it should be?

[AlexO]

it means the GetActiveView() stopped worked in your program. Check carefully what it does (if you have source control check what it used to do)

[Joao Paulo Figueira]

Try to use a dynamic_cast. If the returned value is NULL, then the pointer is not of that class.

[raner]

what is source control?...i thought it simply gets the MainFrame pointer and then the active view's pointer? anyway...i don't understand how GetActiveView() can just stop working?

[raner]

How do i use dynamic_cast?...sorry,i've heard of it but i've never tried anything like that..

[Joao Paulo Figueira]

Do this:

pView = dynamic_cast<CMy3027View*>(pMF->GetActiveView());
if(pView)
m_numOfValues= pView->m_imageIndex;

You might have to turn on the RTTI option in VC.

[raner]

It ran into exception handling error while executing pView = dynamic_cast(pMF->GetActiveView()); Anyway...is there a better way to obtain member variables of a CView class then?

[palbano]

good grief :mad: the code you posted is horribly wrong considering it was provided to you correctly

"No matter where you go, there your are..." - Buckaoo Banzi

-pete

[raner]

;Poops...i mean i did run the right statement(that below) when i got an exception error. pView = dynamic_cast(pMF->GetActiveView());

[palbano]

oh, u missed the "display this message as-is (no HTML)" check box. sorry :-O did you turn on the RTTI build option?

"No matter where you go, there your are..." - Buckaoo Banzi

-pete

[raner]

:-D i c i c yes i did enable it, under project->settings->c++ language...