Question

If I have classes A and B, how can I create a reference to B inside of A? I read that you need use a pointer or a reference, but I can’t find out more than that. Here’s an example of what I’m talking about:

class B;

class A {
    public: 

    B * b_pointer;

    void setSelf(B * given_b_pointer) {
        b_pointer = given_b_pointer;
    };

    void printBName() {
        print (b_pointer.my_name);
    };
};

class B {
    public:

    string my_name;

    void setSelf(string my_given_name) {
        my_name = my_given_name;
    };
}

This gives me several errors. What am I doing wrong, and how can I fix it?

EDIT: The relevant error message:

error: request for member ‘my_name’ in ‘((B*)this)->A::b_pointer’, which
is of non-class type ‘B*’.

Error message slightly edited to replace actual class names with psuedo-class names.

Answer 1

[Updated] You need to forward declare class B and you can not use any of B’s members in the class until it has been declared so move the declaration of printBName to the code file.

class B; //Forward declaration

class A {
    public: 
    B * b_ref;

    ...

    void printBName(); //Need to forward declare this as well
};

class B {
    ...
};

//Now define printBName
void A::printBName(){
    print (b_ref->my_name);// use -> to dereference b_ref
}