CODEWITHSUNDEEP
c++operator-overloadingthis
blisteringbarnacles
blisteringbarnacles

Reputation: 5

Unable to use overloaded [] operator on an object using the this pointer

I'm having issues with the overloaded + operator and the overloaded [] operator. The [] function works fine when used on the OrderedList right object but I cannot get it to return the correct value when used with the this pointer.

The way the code works in main is something like: list3 = list1 + list2

where list2 becomes 'right' in the parameter list, and I am trying to use the this pointer to get the value at the subscript for list1.

The error I'm getting is "cannot convert OrderedList to double in assignment" but I am unsure why it is trying to assign an OrderedList?

Any help much appreciated, thanks.

OrderedList OrderedList::operator+(OrderedList &right)
{
    int size1 = this -> _size;
    int size2 = right.getSize();
    double x, y;
    y = right[size2];
    x = this[size1];
    OrderedList list3;
    return list3;
}

double OrderedList::operator[](int subscript) const // returns rvalue 
{
    int x = OrderedList::_size;
    if (subscript > x)
    {
        cout << "Error: number is bigger than the size of the list" << endl;
    }
    else
    {
        Node* temporary = OrderedList::getListHead();
        for (int counter = 1; counter < subscript; counter++)
        {
            temporary = temporary -> next;
        }
        double nodeValue = temporary -> item;
        return nodeValue;
    }
}

Upvotes: 0

Views: 64

Answers (2)

clcto
clcto

Reputation: 9648

this is a pointer so why you try to do this[size1] it is doing pointer arithmetic. Think:

int a[] = {0, 1};
int *b[2] = &a;

To get to the actual data from b we must derefence it first:

int c = (*b)[1];

Likewise here we must dereference this:

x = (*this)[size1];

Upvotes: 3

Bathsheba
Bathsheba

Reputation: 234875

this->operator[](/*your parameters here*/) will work.

You can drop this-> although it can make things less clear.

(this[size1] will perform some nasty pointer arithmetic - equivalent to this + size1: therefore almost certainly accessing memory you don't own).

Upvotes: 0

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