overload.c

this is a gcc file, you can download it and learn its usetility, for further detail please look at t

// Build don't link: 
// GROUPS passed overloading
enum bar {};

void operator+ (int, int);// ERROR - .*
void operator+ (bar&, int);

template <class T> void operator+ (int b, T& t) { return b; }
void operator+ (int, bar&);

template <class T> class foo
{
public:
  friend void operator+ <> (int, T&);
};

class baz;

class foo<int>;
class foo<baz>;