Globals in MFC

MFC class framework makes possible to work easily with global variables and functions.
Let’s declare a static member variable or function in the CWinApp derived class. It is
accessible from all classes.

Example:

// MyApp.h

class CMyApp : public CWinApp
{
public:
  CMyApp();

  static int g_nMyVariable;      // declaration
  static void g_MyFunction();    // declaration
  ...
  etc
  ...
};

// MyApp.cpp

int CMyApp::g_nMyVariable = NULL;     // definition & initialization

void CMyApp::g_MyFunction()        // definition
{
}

Now the variable and the function are accessible through the syntax CMyApp::g_nMyVariable or CMyApp::g_MyFunction from any other class…