Class passing itself as a parameter

Question

So I've been trying to learn C++ for the past couple weeks. I tend to think in java logic when coding in C++.

So say in java I have this code:

public class Entity {
    public Entity(){
        Foobar foobar = new Foobar(this);
    }

    public void randomMethod(){
        System.out.println("I am an entity");
    }
}

public class Foobar{
    public Foobar(Entity e){
        e.randomMethod();
    }
}

When I create an instance of Foobar, I want to pass the Entity class it was instantiated in, to the Foobar constructor. I'm having a hard time achieving the same code in C++.

EDIT Basically, I want objects, that are instantiated in another class, to know about it's container class.

Answer 1

This is a C++ version of the Java code in the question. Hope this helps.

class Entity {
public:
    Entity();
    void randomMethod();
};

class Foobar : public Entity {
public:
    Foobar(Entity *e);
};

Foobar::Foobar(Entity *e) {
    e->randomMethod();
}

Entity::Entity() {
    Foobar *foobar = new Foobar(this);
}

void Entity::randomMethod() {
    std::cout << "I am an entity";
}

Answer 2

Unlike Java (which does it invisible), in C++ you have to indicate pointers yourself.

If you want to reference an existing object you will have to add & when calling the method and you'll have to specify the parameter with * to indicate it is a pointer.

public: Foobar(Entity* e)
{ // logic here
}

public: Entity() {
    Foobar foobar = new Foobar(this);
}