A Global Application Object

To make your application class available and accessible to the objects of your application, you must declare a global variable from it and there must be only one variable of your application. This variable is of the type of the class derived from CWinApp. Here is an example:

class CSimpleApp : public CWinApp
{
};

CSimpleApp MyApplication;

As you can see, you can name this global variable anything you want. By tradition, in Microsoft Visual C++, this variable is named theApp. Here is an example:

CSimpleApp theApp;

To get a pointer to this variable from anywhere in your application, call the AfxGetApp() framework function. Its syntax is:

CWinApp* AfxGetApp();

To implement the role of the Win32's WinMain() function, the framework uses its own implementation of this function and the MFC provides it as AfxWinInit(). It is declared as follows:

BOOL AFXAPI AfxWinInit(HINSTANCE hInstance,
         HINSTANCE hPrevInstance,
                       LPTSTR lpCmdLine,
         int nCmdShow);

As you can see, the Win32's WinMain() and the MFC's AfxWinInit() functions use the same arguments.