我发现这一句：CDialog::PostNcDestroy();可有可无，请问这是为什么？

[weifirst118]

void CDlgTbmj::PostNcDestroy()
{
delete this;
//CDialog::PostNcDestroy();
}

我发现这一句：CDialog::PostNcDestroy();可有可无，请问这是为什么？

[DentistryDoctor]

都已经delete this;了当然不需要了。

[weifirst118]

那为什么写上也不出错呢？

[dreamy]

MSDN说：
1， Use this function if you wish to do customized allocation of CWnd-derived objects.

2，When destroying a Windows window, the last Windows message sent to the window is WM_NCDESTROY. The default CWnd handler for that message (CWnd::OnNcDestroy) will detach the HWND from the C++ object and call the virtual function PostNcDestroy. Some classes override this function to delete the C++ object.

The default implementation of CWnd::PostNcDestroy does nothing which is appropriate for window objects allocated on the stack frame or embedded in other objects. This is not appropriate for window objects that are designed to be allocated by themselves on the heap (not embedded in other C++ object).

Those classes that are designed to be allocated by themselves on the heap override the PostNcDestroy member function to perform a "delete this". This statement will free any C++ memory associated with the C++ object. Even though the default CWnd destructor calls DestroyWindow if m_hWnd is non-NULL, this does not lead to infinite recursion since the handle will be detached and NULL during the cleanup phase.

[shadowWind]

mark