Declare an object even before that class is created

Question

Is there anyway to declare an object of a class before the class is created in C++? I ask because I am trying to use two classes, the first needs to have an instance of the sec

Answer 1

You can't declare an instance of an undefined class but you can declare a pointer to one:

class A;  // Declare that we have a class A without defining it yet.

class B
{
public:
    A *itemA;
};

class A
{
public:
    B *itemB;
};