class A; //forward defined in class B.h
class B
{
private:

vector<B> v1;
vector<B> v2[3];

public:
void Display()
{
cout<<v1[0].display()
}

}


I get error message forward Declaration of class A;

What is going on here. Is there a way I could initialize all the vectors of type B to be set to NULL in the constructor?