#include <iostream>

using namespace std;

int default_global_vbl = 1;
static int static_global_vbl = 2;
extern int extern_global_vbl;         // to initialize here wouldn't make sense

void default_fn ();
extern void extern_fn ();
static void static_fn ();

//*******************************************************

int main()

{

  cout << "default_global_vbl= " << default_global_vbl << endl;
  cout << "static_global_vbl = " << static_global_vbl  << endl;
  cout << "extern_global_vbl = " << extern_global_vbl  << endl << endl;

  default_global_vbl = 4;
  static_global_vbl = 5;
  extern_global_vbl = 6;

  cout << "default_global_vbl= " << default_global_vbl << endl;
  cout << "static_global_vbl = " << static_global_vbl  << endl;
  cout << "extern_global_vbl = " << extern_global_vbl  << endl << endl;

  static_fn ();
  extern_fn ();
  default_fn ();

return 0;

}

//*******************************************************

// this function must be defined here because its name will not be
// exported to linker

void static_fn()
{
  cout << "I am in static_fn" << endl;

  cout << "default_global_vbl= " << default_global_vbl << endl;
  cout << "static_global_vbl = " << static_global_vbl  << endl;
  cout << "extern_global_vbl = " << extern_global_vbl  << endl << endl;
}