Help With Linked Lists

[owmn]

Derive the class intLinkedList from the class unorderedLinkedList as follows:

class intLinkedList: public unorderedLinkedList<int> {
public:
void splitEvensOddsList(intLinkedList &evensList, intLinkedList &oddsList);
//Function to rearrange the nodes of the linked list so
//that evenList consists of even integers and oddList
//consists of odd integers.
//Postcondition: evenList consists of even integers.
// oddList consists of odd integers.
// The original list is empty.
};
Also write the definition of the function splitEvensOddsList. Note that this function does not create any new node, it only rearranges the nodes of the original list so that nodes with even integers are in evensList and nodes with odd integers are in oddsList.

//intLinkedList.h
#ifndef H_intLinkedList
#define H_intLinkedList  

#include "unorderedLinkedList.h"
 
using namespace std;

class intLinkedList: public unorderedLinkedList<int>
{
public:
    // part a
    void splitEvensOddsList(intLinkedList &evensList, intLinkedList &oddLsist);
      //Function to rearrange the nodes of the linked list so  
      //that evensList consists of even integers and oddsList 
      //consists of odd integers. 
      //Postcondition: evensList consists of even integers.
      //               oddsList consists of odd integers.
      //               The original list is empty.  
};


// part a
void intLinkedList::splitEvensOddsList(intLinkedList &evensList, intLinkedList &oddsList) {

    // write the definition for your splitEvenOddList function here

}//end splitEvenOddList

#endif 

//main.cpp
//This program tests various operation of a linked list
//34 62 21 10 15 90 66 53 7 120 88 36 90 11 17 24 10 -999 

#include <iostream>
#include "intLinkedList.h"

using namespace std; 

// part b
int main()
{
    intLinkedList list;

    intLinkedList evensList;
    intLinkedList oddsList;

    int num;

    cout << "Enter integers ending with -999" << endl;
    cin >> num;

    while (num != -999)
    {
        list.insertLast(num);
        cin >> num;
    }

    cout << endl;

    cout << "list: ";
    list.print();
    cout << endl;

    list.splitEvensOddsList(evensList, oddsList);

    cout << "evensList: ";
    evensList.print();
    cout << endl;

    cout << "oddsList: ";
    oddsList.print();
    cout << endl;

    return 0;
}

//unorderedLinkedList.h

#ifndef H_UnorderedLinkedList
#define H_UnorderedLinkedList  

#include "linkedList.h"
 
using namespace std;

template <class Type> 
class unorderedLinkedList: public linkedListType<Type>
{
public:
    bool search(const Type& searchItem) const;
      //Function to determine whether searchItem is in the list.
      //Postcondition: Returns true if searchItem is in the 
      //               list, otherwise the value false is 
      //               returned.

    void insertFirst(const Type& newItem);
      //Function to insert newItem at the beginning of the list.
      //Postcondition: first points to the new list, newItem is
      //               inserted at the beginning of the list,
      //               last points to the last node in the  
      //               list, and count is incremented by 1.

    void insertLast(const Type& newItem);
      //Function to insert newItem at the end of the list.
      //Postcondition: first points to the new list, newItem 
      //               is inserted at the end of the list,
      //               last points to the last node in the 
      //               list, and count is incremented by 1.

    void deleteNode(const Type& deleteItem);
      //Function to delete deleteItem from the list.
      //Postcondition: If found, the node containing 
      //               deleteItem is deleted from the list.
      //               first points to the first node, last
      //               points to the last node of the updated 
      //               list, and count is decremented by 1.
};


template <class Type>
bool unorderedLinkedList<Type>::
                   search(const Type& searchItem) const
{
    nodeType<Type> *current; //pointer to traverse the list
    bool found = false;
    
    current = this->first; //set current to point to the first 
                     //node in the list

    while (current != nullptr && !found)    //search the list
        if (current->info == searchItem) //searchItem is found
            found = true;
        else
            current = current->link; //make current point to
                                     //the next node
    return found; 
}//end search

template <class Type>
void unorderedLinkedList<Type>::insertFirst(const Type& newItem)
{
    nodeType<Type> *newNode; //pointer to create the new node

    newNode = new nodeType<Type>; //create the new node

    newNode->info = newItem;    //store the new item in the node
    newNode->link = this->first;      //insert newNode before first
    this->first = newNode;            //make first point to the
                                //actual first node
    this->count++;                    //increment count

    if (this->last == nullptr)   //if the list was empty, newNode is also 
                        //the last node in the list
        this->last = newNode;
}//end insertFirst

template <class Type>
void unorderedLinkedList<Type>::insertLast(const Type& newItem)
{
    nodeType<Type> *newNode; //pointer to create the new node

    newNode = new nodeType<Type>; //create the new node

    newNode->info = newItem;  //store the new item in the node
    newNode->link = nullptr;     //set the link field of newNode
                              //to nullptr

    if (this->first == nullptr)  //if the list is empty, newNode is 
                        //both the first and last node
    {
        this->first = newNode;
        this->last = newNode;
        this->count++;        //increment count
    }
    else    //the list is not empty, insert newNode after last
    {
        this->last->link = newNode; //insert newNode after last
        this->last = newNode; //make last point to the actual 
                        //last node in the list
        this->count++;        //increment count
    }
}//end insertLast


template <class Type>
void unorderedLinkedList<Type>::deleteNode(const Type& deleteItem)
{
    nodeType<Type> *current; //pointer to traverse the list
    nodeType<Type> *trailCurrent; //pointer just before current
    bool found;

    if (this->first == nullptr)    //Case 1; the list is empty. 
        cout << "Cannot delete from an empty list."
             << endl;
    else
    {
        if (this->first->info == deleteItem) //Case 2 
        {
            current = this->first;
            this->first = this->first->link;
            this->count--;
            if (this->first == nullptr)    //the list has only one node
                this->last = nullptr;
            delete current;
        }
        else //search the list for the node with the given info
        {
            found = false;
            trailCurrent = this->first;  //set trailCurrent to point
                                   //to the first node
            current = this->first->link; //set current to point to 
                                   //the second node

            while (current != nullptr && !found)
            {
                if (current->info != deleteItem) 
                {
                    trailCurrent = current;
                    current = current-> link;
                }
                else
                    found = true;
            }//end while

            if (found) //Case 3; if found, delete the node
            {
                trailCurrent->link = current->link;
                this->count--;

                if (this->last == current)   //node to be deleted 
                                       //was the last node
                    this->last = trailCurrent; //update the value 
                                         //of last
                delete current;  //delete the node from the list
            }
            else
                cout << "The item to be deleted is not in "
                     << "the list." << endl;
        }//end else
    }//end else
}//end deleteNode


#endif 

[owmn]

//linkedList.h
#ifndef H_LinkedListType
#define H_LinkedListType  
 
#include <iostream>
#include <cassert>

using namespace std;

//Definition of the node

template <class Type>
struct nodeType
{
  Type info;
  nodeType<Type> *link;
};

template <class Type>
class linkedListIterator
{
public:
   linkedListIterator();
     //Default constructor
     //Postcondition: current = nullptr;

   linkedListIterator(nodeType<Type> *ptr);
     //Constructor with a parameter.
     //Postcondition: current = ptr;

   Type operator*();
     //Function to overload the dereferencing operator *.
     //Postcondition: Returns the info contained in the node.

   linkedListIterator<Type> operator++();    
     //Overload the pre-increment operator.
     //Postcondition: The iterator is advanced to the next 
     //               node.

   bool operator==(const linkedListIterator<Type>& right) const; 
     //Overload the equality operator.
     //Postcondition: Returns true if this iterator is equal to 
     //               the iterator specified by right, 
     //               otherwise it returns the value false.

   bool operator!=(const linkedListIterator<Type>& right) const; 
     //Overload the not equal to operator.
     //Postcondition: Returns true if this iterator is not  
     //               equal to the iterator specified by  
     //               right; otherwise it returns the value 
     //               false.

private:
   nodeType<Type> *current; //pointer to point to the current 
                            //node in the linked list
};

template <class Type>
linkedListIterator<Type>::linkedListIterator()
{
    this->current = nullptr;
}

template <class Type>
linkedListIterator<Type>::linkedListIterator(nodeType<Type> *ptr)
{
    current = ptr;
}

template <class Type>
Type linkedListIterator<Type>::operator*()
{
    return this->current->info;
}

template <class Type>
linkedListIterator<Type> linkedListIterator<Type>::operator++()   
{
    this->current = this->current->link;

    return *this;
}

template <class Type>
bool linkedListIterator<Type>::operator==
               (const linkedListIterator<Type>& right) const
{
    return (this->current == right.current);
}

template <class Type>
bool linkedListIterator<Type>::operator!=
                 (const linkedListIterator<Type>& right) const
{    return (this->current != right.current);
}


//*****************  class linkedListType   ****************

template <class Type>
class linkedListType
{
public:
    const linkedListType<Type>& operator=
                         (const linkedListType<Type>&);  
      //Overload the assignment operator.

    void initializeList(); 
      //Initialize the list to an empty state.
      //Postcondition: first = nullptr, last = nullptr, count = 0;

    bool isEmptyList() const;
      //Function to determine whether the list is empty. 
      //Postcondition: Returns true if the list is empty,
      //               otherwise it returns false.

    void print() const;
      //Function to output the data contained in each node.
      //Postcondition: none

    int length() const;
      //Function to return the number of nodes in the list.
      //Postcondition: The value of count is returned.

    void destroyList();
      //Function to delete all the nodes from the list.
      //Postcondition: first = nullptr, last = nullptr, count = 0;

    Type front() const; 
      //Function to return the first element of the list.
      //Precondition: The list must exist and must not be 
      //              empty.
      //Postcondition: If the list is empty, the program
      //               terminates; otherwise, the first 
      //               element of the list is returned.

    Type back() const; 
      //Function to return the last element of the list.
      //Precondition: The list must exist and must not be 
      //              empty.
      //Postcondition: If the list is empty, the program
      //               terminates; otherwise, the last  
      //               element of the list is returned.

    virtual bool search(const Type& searchItem) const = 0;
      //Function to determine whether searchItem is in the list.
      //Postcondition: Returns true if searchItem is in the 
      //               list, otherwise the value false is 
      //               returned.

    virtual void insertFirst(const Type& newItem) = 0;
      //Function to insert newItem at the beginning of the list.
      //Postcondition: first points to the new list, newItem is
      //               inserted at the beginning of the list,
      //               last points to the last node in the list, 
      //               and count is incremented by 1.

    virtual void insertLast(const Type& newItem) = 0;
      //Function to insert newItem at the end of the list.
      //Postcondition: first points to the new list, newItem 
      //               is inserted at the end of the list,
      //               last points to the last node in the list,
      //               and count is incremented by 1.

    virtual void deleteNode(const Type& deleteItem) = 0;
      //Function to delete deleteItem from the list.
      //Postcondition: If found, the node containing 
      //               deleteItem is deleted from the list.
      //               first points to the first node, last
      //               points to the last node of the updated 
      //               list, and count is decremented by 1.

    linkedListIterator<Type> begin();
      //Function to return an iterator at the begining of the 
      //linked list.
      //Postcondition: Returns an iterator such that current is
      //               set to first.

    linkedListIterator<Type> end();
      //Function to return an iterator one element past the 
      //last element of the linked list. 
      //Postcondition: Returns an iterator such that current is
      //               set to nullptr.

    linkedListType(); 
      //default constructor
      //Initializes the list to an empty state.
      //Postcondition: first = nullptr, last = nullptr, count = 0; 

    linkedListType(const linkedListType<Type>& otherList); 
      //copy constructor

    ~linkedListType();   
      //destructor
      //Deletes all the nodes from the list.
      //Postcondition: The list object is destroyed. 

protected:
    int count;   //variable to store the number of 
                 //elements in the list
    nodeType<Type> *first; //pointer to the first node of the list
    nodeType<Type> *last;  //pointer to the last node of the list

private: 
    void copyList(const linkedListType<Type>& otherList); 
      //Function to make a copy of otherList.
      //Postcondition: A copy of otherList is created and
      //               assigned to this list.
};


template <class Type>
bool linkedListType<Type>::isEmptyList() const
{
    return (first == nullptr);
}

template <class Type>
linkedListType<Type>::linkedListType() //default constructor
{
    first = nullptr;
    last = nullptr;
    count = 0;
}

[owmn]

//above cont.
template <class Type>
void linkedListType<Type>::destroyList()
{
    nodeType<Type> *temp;   //pointer to deallocate the memory
                            //occupied by the node
    while (first != nullptr)   //while there are nodes in the list
    {
        temp = first;        //set temp to the current node
        first = first->link; //advance first to the next node
        delete temp;   //deallocate the memory occupied by temp
    }
    last = nullptr; //initialize last to nullptr; first has already
                 //been set to nullptr by the while loop
    count = 0;
}

template <class Type>
void linkedListType<Type>::initializeList()
{
  destroyList(); //if the list has any nodes, delete them
}

template <class Type>
void linkedListType<Type>::print() const
{
    nodeType<Type> *current; //pointer to traverse the list

    current = first;    //set current so that it points to 
                        //the first node
    while (current != nullptr) //while more data to print
    {
        cout << current->info << " ";
        current = current->link;
    }
}//end print

template <class Type>
int linkedListType<Type>::length() const
{
    return count;
}  //end length

template <class Type>
Type linkedListType<Type>::front() const
{   
    assert(first != nullptr);

    return first->info; //return the info of the first node 
}//end front

template <class Type>
Type linkedListType<Type>::back() const
{   
    assert(last != nullptr);

    return last->info; //return the info of the last node 
}//end back

template <class Type>
linkedListIterator<Type> linkedListType<Type>::begin()
{
    linkedListIterator<Type> temp(first);

    return temp;
}

template <class Type>
linkedListIterator<Type> linkedListType<Type>::end()
{
    linkedListIterator<Type> temp(nullptr);

    return temp;
}

template <class Type>
void linkedListType<Type>::copyList
                   (const linkedListType<Type>& otherList) 
{
    nodeType<Type> *newNode; //pointer to create a node
    nodeType<Type> *current; //pointer to traverse the list

    if (first != nullptr) //if the list is nonempty, make it empty
       destroyList();

    if (otherList.first == nullptr) //otherList is empty
    {
        first = nullptr;
        last = nullptr;
        count = 0;
    }
    else
    {
        current = otherList.first; //current points to the 
                                   //list to be copied
        count = otherList.count;

            //copy the first node
        first = new nodeType<Type>;  //create the node

        first->info = current->info; //copy the info
        first->link = nullptr;        //set the link field of 
                                   //the node to nullptr
        last = first;              //make last point to the
                                   //first node
        current = current->link;     //make current point to
                                     //the next node

           //copy the remaining list
        while (current != nullptr)
        {
            newNode = new nodeType<Type>;  //create a node
            newNode->info = current->info; //copy the info
            newNode->link = nullptr;       //set the link of 
                                        //newNode to nullptr
            last->link = newNode;  //attach newNode after last
            last = newNode;        //make last point to
                                   //the actual last node
            current = current->link;   //make current point 
                                       //to the next node
        }//end while
    }//end else
}//end copyList

template <class Type>
linkedListType<Type>::~linkedListType() //destructor
{
   destroyList();
}//end destructor

template <class Type>
linkedListType<Type>::linkedListType
                      (const linkedListType<Type>& otherList)
{
    first = nullptr;
    copyList(otherList);
}//end copy constructor

         //overload the assignment operator
template <class Type>
const linkedListType<Type>& linkedListType<Type>::operator=
                      (const linkedListType<Type>& otherList)
{ 
    if (this != &otherList) //avoid self-copy
    {
        copyList(otherList);
    }//end else

     return *this; 
}

#endif 

[lastchance]

So, having splashed your teacher's work across three successive posts without their permission, what's your problem?

[MikeyBoy]

Wow. It's almost as if you completely ignored everything people said on your last thread, and learnt nothing whatsoever.

But that can't be true... can it?

[dhayden]

One thing that most people will miss: you should empty out evensList and oddsList before adding items to them. Put another way, don't assume that evensList and oddList are empty upon entry.

This is very simple code to write: in pseudo-code:

empty out evensList
empty out oddsList
while there are items in the current list {
    unlink the first item;
    link it into oddsList or evensList as appropriate.
}

Note that you won't be using any of the methods written so far because none of them deal with moving nodes around, only items.