Operator Overloading for a Nested class

[darkhipo]

Hi,

I'm trying to overload the << operator for a nested private class.

I have a situation like:

class A
{
public:
class B
{
private:
int i;
};
};
ostream& operator<<(ostream& output, const A::B& b)
{
cout << "I= " << b.i ;
}
Where the last command denies me access toi because of its private access level.

How would I rewrite the operator overload above to allow me to do this?

[Bazzy]

Just declare ostream& operator<<(ostream& output, const A::B& b)
as friend in class B

[Umz]

Its not the operator, its the private thats causing the problem, use an access function inside the class to allow access the the private.

Something like:

void display(ostream& o) {
   o << "I= " << i << endl;
}

If you use this inside the class then you overcome the private access problem, then you can overload the operator to do:

ostream& operator<<(ostream& o, const A::B& b) {
   b.display(o);
   return o;
}

Its generally not a great idea to just add friends to classes, although it should be fine with the ostream's it could cause problems with other things.

[jsmith]

Making operator<< a friend is typically an acceptable solution, although Umz's solution works too.