Access other classes through the Global handle (extern hwnd)

Generally, we define a class object to define the member variables and functions of the class. This is relatively simple, for example:
Cpage1 m_page1;
Then, you can use m_page1 to access the defined functions in the cpage1 class, such as m_page1.add (2, 3 );

But what if I need to access the functions in the main window class in the cpage1 class?
We can access it through a handle.

1. define it in test. H (main program header file) or stdafx. h.

Extern hwnd g_hwnd;

2. In testdlg. cpp, ensure that the test. h header file is referenced and

Hwnd g_hwnd;

3. In ctestdlg: oninitdialog ()

G_hwnd = m_hwnd;

So it can be referenced anywhere in cpage1, for example:

(Ctestdlg *) fromhandle (g_hwnd)-> m_page1.showwindow (sw_hide );

Of course, because g_hwnd is also the handle of the Main Window of the program, g_hwnd can also be written as afxgetmainwnd ()-> m_hwnd

This method is common in the same class. For example, cpage1, cpage2, and cpage3 are defined. They reference each other using a handle.