CODEWITHSUNDEEP
c++listconstructorcopy
user2932450
user2932450

Reputation: 71

Is this copy constructor creating an identical and independent deep copy of the input object?

I have the following copy constructor made for a Polynomial class. The constructor is supposed to create an independent deep copy of the input Polynomial object. Is the copy constructor actually doing this or is it creating a shallow copy? 

Polynomial::Polynomial(const Polynomial &p) {
    cout << "Enter method\n";
    if(p.head != NULL) {
        cout << "Enter if\n";
        Node* n = p.head;

        int nDegree = n->degree;
        while(n != NULL) {
             this->add(n->coeff, n->degree);
             nDegree--;
             n = n->next;
        }
        n = NULL;
    }   
}

Here is the add method: 

void Polynomial::add(const float& coeff, const int& degree) { 
    Node *temp = new Node(coeff, degree, NULL, NULL);
    temp->coeff = coeff;
    temp->degree = degree;
    if(tail == NULL) {
        head = temp;
        tail = temp;
        arrSize++;
    }
    else {
        temp->prev = tail;
        tail->next = temp;
        tail = temp;
        arrSize++;      
    } 
 }

Upvotes: 0

Views: 296

Answers (1)

Christophe
Christophe

Reputation: 73456

Polynomial::add() creates a new node and inserts it in a linked list.

Your copy constructor iterates through the existing linked list to add notes to the list being consutructed.

So it's a deep copy and not a shallow copy.

Remarks:

Consider initializing explicitey head an tail to NULL in your copy constructor, before starting to add nodes.

Depending on the Node constructor, apparently using coeff and degree you may consider not to redundantly reassign these values to temp members.

The purpose of nDegree--; in your loop is not completely clear to me. I think you could drop it.

Upvotes: 1

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