Question

I'm not sure how to fix my code I keep getting an error with rhs.begin. I linked the header file and the test file, THESE TWO CANNOT be changed they have absolutely no errors in them. To clarify I ONLY need help with the copy constructor part.

/* ~~~~~~~~~~~~list.cpp~~~~~~~~~~~~~~~*/

#include
#include "list.h"

using namespace std;

Node::Node(string element)
{
data = element;
previous = nullptr;
next = nullptr;
}

List::List()
{
first = nullptr;
last = nullptr;
}

List::List(const List& rhs)// Copy constructor - homework THIS IS THE ONLY PART THAT CAN BE CHANGED IM NOT SURE WHAT IM DOING WRONG
{
Iterator oldIt = rhs.begin();
first = nullptr;
last = nullptr;
while (oldIt.position != nullptr){
   push_back(oldIt.get());
   oldIt.next();
}
}

void List::push_back(string element)
{
Node* new_node = new Node(element);
if (last == nullptr) // List is empty
{
first = new_node;
last = new_node;
}
else
{
new_node->previous = last;
last->next = new_node;
last = new_node;
}
}

void List::insert(Iterator iter, string element)
{
if (iter.position == nullptr)
{
push_back(element);
return;
}

Node* after = iter.position;
Node* before = after->previous;
Node* new_node = new Node(element);
new_node->previous = before;
new_node->next = after;
after->previous = new_node;
if (before == nullptr) // Insert at beginning
{
first = new_node;
}
else
{
before->next = new_node;
}
}

Iterator List::erase(Iterator iter)
{
Node* remove = iter.position;
Node* before = remove->previous;
Node* after = remove->next;
if (remove == first)
{
first = after;
}
else
{
before->next = after;
}
if (remove == last)
{
last = before;
}
else
{
after->previous = before;
}
delete remove;
Iterator r;
r.position = after;
r.container = this;
return r;
}

Iterator List::begin()
{
Iterator iter;
iter.position = first;
iter.container = this;
return iter;
}

Iterator List::end()
{
Iterator iter;
iter.position = nullptr;
iter.container = this;
return iter;
}

Iterator::Iterator()
{
position = nullptr;
container = nullptr;
}

string Iterator::get() const
{
return position->data;
}

void Iterator::next()
{
position = position->next;
}

void Iterator::previous()
{
if (position == nullptr)
{
position = container->last;
}
else
{
position = position->previous;
}
}

bool Iterator::equals(Iterator other) const
{
return position == other.position;
}

/*~~~~~~~~~~~~~~lish.h~~~~~~~~~~~~~*/

#ifndef LIST_H

#define LIST_H

#include

using namespace std;

class List;

class Iterator;

//template

class Node

{

public:

/**

Constructs a node with a given data value.

@param element the data to store in this node

*/

Node(string element); // Node(T element)

// Node(T data, Node* n, Node* n);

private:

string data; // T data;

Node* previous;

Node* next;

friend class List;

friend class Iterator;

};

class List

{

public:

/**

Constructs an empty list.

*/

List();

List(const List& rhs); // Homework

/*

Appends an element to the list.

@param element the value to append

*/

void push_back(string element);

/**

Inserts an element into the list.

@param iter the position before which to insert

@param element the value to insert

*/

void insert(Iterator iter, string element);

/**

Removes an element from the list.

@param iter the position to remove

@return an iterator pointing to the element after the

erased element

*/

Iterator erase(Iterator iter);

/**

Gets the beginning position of the list.

@return an iterator pointing to the beginning of the list

*/

Iterator begin();

/**

Gets the past-the-end position of the list.

@return an iterator pointing past the end of the list

*/

Iterator end();

private:

Node* first;

Node* last;

friend class Iterator;

};

class Iterator

{

public:

/**

Constructs an iterator that does not point into any list.

*/

Iterator();

/**

Looks up the value at a position.

@return the value of the node to which the iterator points

*/

string get() const;

/**

Advances the iterator to the next node.

*/

void next();

/**

Moves the iterator to the previous node.

*/

void previous();

/**

Compares two iterators.

@param other the iterator to compare with this iterator

@return true if this iterator and other are equal

*/

bool equals(Iterator other) const;

private:

Node* position;

List* container;

friend class List;

};

#endif

/*~~~~~~~list_test.cpp~~~~~~*/

#include

#include

#include "list.h"

using namespace std;

int main()

{

List names;

names.push_back("Tom");

names.push_back("Diana");

names.push_back("Harry");

names.push_back("Juliet");

// Add a value in fourth place

Iterator pos = names.begin();

pos.next();

pos.next();

pos.next();

names.insert(pos, "Romeo");

// Remove the value in second place

pos = names.begin();

pos.next();

names.erase(pos);

List names_copy(names); //Copy constructor - homework

names_copy.push_back("Shakespeare");

// Verify that Shakespeare was inserted.

cout << "Printing new list" << endl;

for (pos = names_copy.begin(); !pos.equals(names.end()); pos.next())

{

cout << pos.get() << endl; //

}

cout << "Printing original list " << endl;

for (pos = names.begin(); !pos.equals(names.end()); pos.next())

{

cout << pos.get() << endl;

}

return 0;

}

Answer 1

Copy Constructor

List::List(const List& rhs)

{

Node *temp = rhs.first;

while (temp != nullptr){

this->push_back(temp->data);

temp = temp->next;

}

}

===========================================

SEE OUTPUT

Thanks, PLEASE COMMENT if there is any concern.