C / C++ / MFC

class First {
	static char *szName;
};

char *First::szName = "First";

class Second {
	static char *szName;
};

char *Second::szName = "Second";


class User {
	static char *aszNames[];
};

char *User::aszNames[] = {First::szName, Second::szName};

// First.h
class First {
	...
	static int i;
	static int j;
	...
};
// First.cpp
int First::i = 7;
int First::j = Second::q;
// Second.h
class Second {
	...
	static int q;
	static int r;
	...
};
// Second.cpp
int Second::q = First::i;
int Second::r = First::j;

// First.h
class First
{
	...
	static int i();
	static int j();
	...
};
// First.cpp
int First::i()
{
  static int i_ = 7;
  return i_;
}
int First::j()
{
  static int j_ = Second::q();
  return j_;
}
// Second.h
class Second
{
	...
	static int q();
	static int r();
	...
};
// Second.cpp
int Second::q()
{
  static int q_ = First::i();
  return q_;
}
int Second::r()
{
  static int r_ = First::j();
  return r_;
}