C++ deep copying with objects

Question

Good morning. I am having trouble understanding the logic behind deep and shallow copying with objects in C++ in a shared project, so I have created the following example.

int main() {
    ObjectAType* objecta = ObjectAType::New();
    ObjectBType* objectb = ObjectBType::New();

    // some operation to populate data members of object a
    objecta->Operation();

    // assume I have accessors to return datamembers of object a
    // I wish to make a deep copy of SOME of those data members into object b
    objectb->AlignWithA(objecta);

    objecta->Delete();
    objectb->Delete();

    return 0;
}

Now given the object b class function as follows:

public:
void ObjectBType::AlignWithA(ObjectAType* objecta) {
    this->ObjectBDataMember = objecta->DataAccessor();
}
protected:
int ObjectBDataMember;

And the data accessor is just something like this within the class def,

public:
int ObjectAType::DataAccessor() {
    return this->ObjectADataMember;
}
protected:
int ObjectADataMember;

I have a few resulting questions.

1) Since in object b, the data member is declared as

int ObjectBDataMember; 

and not as

int *ObjectBDataMember;

why is the data member accessed as

this->ObjectBDataMember

and not as

this.ObjectBDataMember

?

2) Is this a deep or shallow copy?

I apologize if I have left out important bits. I'm not much of a programmer so things like this easily confuse me. The literature has just confused me further. Thank you for your time.

Answer 1

1. In C++, this is defined as being a (non-modifiable) pointer to the current object. For that reason, you use this->aMember to access aMember. This is independent of the type that aMember has. (Note: Using this->aMember is equivalent to just using aMember as long as there are no local variables or function parameters using that same name).

2. Because ObjectBDataMember is an int, copying it is not referred to as either shallow or deep. Those concepts are only used in the context of copying pointers.

For example:

ObjectBType* b1 = new ObjectBType();

ObjectBType* b2 = b1; // shallow copy. b1 and b2 refer to the same object.
ObjectBType* b3 = new ObjectBType(*b1); /* deep copy. b1 and b3 refer to 
  different objects that happen to have the same value. */