How to avoid deletion of class members after assignment?

Question

I implemented singly linked list using binary-tree concept to insert elements in the list (tree). When I copy the values of a list using assignment like that

Tree<A> list1, list2;

//Filling list1...

list2 = list1;

//Remove all elements of list1 using the implemented remove method...

print(list2); //throws an error as its elements appear to have been removed as well

It seems to also copy the pointers of class members (m_pLeft and m_pRight) of the tree. Does anyone know why ? and how can I avoid it?

template<typename T>
class Tree {

    class ListElem {
    public:

        ListElem(T t) : m_Elem(t) {}
        ListElem(const ListElem&) = delete;
        ListElem& operator=(const ListElem&) = delete;

        T m_Elem;
        ListElem* m_pLeft = nullptr, * m_pRight = nullptr;
    };

public:
    unsigned size() const {
        return this->length;
    }
    void remove(T t)
    {

        if (this->length > 0) 
        {
            this->m_pHead = remove(this->m_pHead, t);
        }

    }

private:

    ListElem* m_pHead = nullptr;
    unsigned length = 0;
    
};

The full code can be found here.

Maybe this answer would help: https://stackoverflow.com/q/4172722/9171697 — ph3rin, Apr 05 '21 at 15:49
Probably `m_pLeft` and `m_pRight` aren't being copied in `list2 = list1;`. Rather, both have the same `m_pHead` pointer to the same `ListElem`, so changing that single `ListItem` head object has effects visible from both `Tree` variables. If `Tree` should be copyable, you'll probably want it to implement "deep copy". I think Ðаn is suggesting that using `std::unique_ptr` instead of raw pointers would be helpful. — aschepler, Apr 05 '21 at 15:50
Please edit a [mcve] into the question, something we can compile. — rustyx, Apr 05 '21 at 16:09
Data types with pointer members very often need non-trivial implementation of special member functions. Follow the "Rule of Five". — Ben Voigt, Apr 08 '21 at 15:28
@BenVoigt I updated the [code](https://codeshare.io/5oR1rM) following _Rule of Five_ can you take a look please? — Brandon, Apr 08 '21 at 16:13

How to avoid deletion of class members after assignment?

0 Answers0