Friends with multiple classes

class B; // forward declaration for the compiler

class A {
friend void frFunction( A& obj1, B& obj2);
private:
int data;
};

class B {
friend void frFunction( A& obj1, B& obj2);
private:
int data;
};

void frFunction( A& obj1, B& obj2 )
{
cout << obj1.data << obj2.data << endl;
}