Memory leakage that is hard to detect

Memory leakage that is hard to detect University of Electronic Science and Technology Zhu Ning ---- Recently, when I used VC ++ to write a screen saver, I was very confused about memory leakage. Later, the problem was solved based on several examples. Let's analyze the cause and solution: ---- The author derives a subclass cdrawwnd from cwnd and adds the following code to the initinstance () of the main program class: m_pMainWnd=new CDrawWnd();m_pMainWnd- >Create(.....);return TRUE; ---- After debugging and running, the VC ++ debugger reports Memory leakage. Obviously, the problem only occurs in the first line of code above. When I wrote the above code, I also suspected that there is no corresponding delete for new, which will lead to heap memory unrecoverable. However, refer to the example of VC ++ 5.0 "hello ", the code of this program is similar to the above, and no other function calls Delete to reclaim heap memory, but it does not cause memory leakage. Check the online help of VC ++ without detailed instructions. It only means that when the window is closed, the virtual function postncdestory is automatically called to reclaim the memory directed by m_pmainwnd. ---- So I tried to call Delete m_pmainwnd in the main program class's destructor, which has no effect. Explicit call of cwnd: destorywindow () does not work either. By referring to the example saver, we found that the implementation code in front of it is exactly the same as the author's. However, it reloads the postncdestory virtual function in the cdrawwnd class, with a line of key code: delete this; ---- In fact, it destroys the cdrawwnd object. ---- So I immediately modified my program, reloaded the postncdestory function in the main window class, and added the above sentence to immediately solve the memory leakage problem. ---- The reason is finally clear. Originally, if the main window class of the program is inherited from cframewnd, the memory occupied by the class object does not need to be manually recycled. In the example of "hello", this is a program. However, if the main window class is directly inherited from the cwnd class, you must consider this issue.