Assertion Error during select of "Close all Other" in context menu

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Dear All,

I am getting assertion error, on implementing the updates for "Close All Others" in MFC Application,, wherein, Tab Document Interface(TDI) has numerous tabs, similar to VS 2008 IDE, and when user right clicks the context menu <<Close All Other>> , which has the following handler ,

The following code will close all except the active tab in the "first" MDI client tab group..

//Mainframe.cpp

Begin_message_map

..............

ON_COMMAND(ID_TAB_CLOSEOTHER, &CMainFrame::OnTabCloseOther)

............

CMainFrame::OnCloseOtherTab()

{

Line 1. const CObList* tabList = &m_wndClientArea.GetMDITabGroups(); 
Line 2: CMFCTabCtrl* pTabWnd = (CMFCTabCtrl*)tabList->GetHead(); 
Line 3. if (pTabWnd != NULL) 
Line 4: { 
Line 5: int iActiveTab = pTabWnd->GetActiveTab();
Line 6: ASSERT_VALID(pTabWnd);
Line 7: for (int i = pTabWnd->GetTabsNum() - 1; i >= 0; i--)
Line 8: {
Line 9: CMDIChildWndEx* pNextWnd = DYNAMIC_DOWNCAST CMDIChildWndEx........................ }
//MainFrame.h 

CMDIChientAreaWnd m_wndClientArea;

The assertion is displayed on execution of Line 2. The following line gets displayed on assertion

return AfxWinMain(hInstance, hPrevInstance, lpCmdLine,nCmdShow);

<<<<Unhandled exception at 0x787d01ec (mfc90d.dll)
in CART.exe: 0xC0000005: Access violation reading location x00000008.>>>>

Please let me know how to correct the above solution.

With Regards,

Posted 11-Jul-11 4:10am

Member 7985084

Updated 11-Jul-11 5:18am

Albert Holguin

v2

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Roger Allen · Answer 1 · 2011-07-11T06:21:00

The documentation for CObList::GetHead() says that the list cannot be empty and would fail.

You are not currently checking the size of the list before getting the head element. Try calling IsEmpty() first to determine whether accessing the head element would be an error.

It may be worth stepping through the code to check the the tabList pointer is valid from the call to GetMDITabGroups

Albert Holguin · Answer 2 · 2011-07-11T07:43:00

Solution 2

AfxWinMain() is the entry point of an MFC application, are you sure you're not accidentally calling this method during startup? You may have a conflict with ID_TAB_CLOSEOTHER or something is calling that directly upon startup but before the members are initialized.

Posted 11-Jul-11 7:43am