LinkedList.cpp

class LinkedList;

class Node {
public:
  // You can do it this way but eehhhh
  friend LinkedList;
  Node(int data): data{data}, next{nullptr} {}
  // Otherwise just use this if you have it
  Node *get_next() { return next; }
private:
  int data;
  Node *next;
};

// IMHO the better way to do it is to have Node be a struct
// Or have Node as an internal class of LinkedList

class LinkedList {
public:
  LinkedList();
  LinkedList(const LinkedList& ll);

  class Iterator {
  public:
    Iterator();
    Iterator operator++() {
      // nullptr checking
      curr = curr->next;
    }
    // yadda yadda

    Iterator operator*();
    Iterator *operator->();
  };

  Iterator begin();
  // NOTE: Make sure it represents the theoretically place after the last
  // Doing stuff to end() is undefined behavior
  // Undefined behavior means: literally anything can happen
  Iterator end();
private:
  Node *head;
};

LinkedList::LinkedList(const LinkedList& ll) {
  // LinkedLists are automatically friends with LinkedLists
  Node *n = ll.head;
  // Iterate over and deep copy...
}