Hi, I was given the following problem, I've almost got it but I've hit a roadblock and having no luck getting past it. Here is the problem im supposed to solve...
The function insert of the class orderedLinkedList does not check if the item to be inserted is already in the list; that is, it does not check for duplicates. Rewrite the definition of the function insert so that before inserting the item it checks weather the item to be inserted is already in the list. If the item is already in the list, the function outputs the appropriate error message.
For some reason my program keeps crashing while trying to add items to the list, i have no idea why, and I'm not skilled enough to figure it out using the debugger, any help is greatly appreciated, all code is below.
Header linkedList.h
#ifndef H_LinkedListType
#define H_LinkedListType
#include <iostream>
#include <cassert>
#include <iterator>
using namespace std;
//Definition of the node
template <class Type>
struct nodeType
{
Type info;
nodeType<Type> *link;
};
//***********************************************************
// Author: D.S. Malik
//
// This class specifies the members to implement an iterator
// to a linked list.
//***********************************************************
template <class Type>
class linkedListIterator
{
public:
linkedListIterator();
//Default constructor
//Postcondition: current = NULL;
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 preincrement 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
// 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
// false.
private:
nodeType<Type> *current; //pointer to point to the current
//node in the linked list
};
template <class Type>
linkedListIterator<Type>::linkedListIterator()
{
current = NULL;
}
template <class Type>
linkedListIterator<Type>::
linkedListIterator(nodeType<Type> *ptr)
{
current = ptr;
}
template <class Type>
Type linkedListIterator<Type>::operator*()
{
return current->info;
}
template <class Type>
linkedListIterator<Type> linkedListIterator<Type>::operator++()
{
current = current->link;
return *this;
}
template <class Type>
bool linkedListIterator<Type>::operator==
(const linkedListIterator<Type>& right) const
{
return (current == right.current);
}
template <class Type>
bool linkedListIterator<Type>::operator!=
(const linkedListIterator<Type>& right) const
{ return (current != right.current);
}
//***********************************************************
// Author: D.S. Malik
//
// This class specifies the members to implement the basic
// properties of a linked list. This is an abstract class.
// We cannot instantiate an object of this class.
//***********************************************************
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 = NULL, last = NULL, 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 = NULL, last = NULL, 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 beginning 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 NULL.
linkedListType();
//default constructor
//Initializes the list to an empty state.
//Postcondition: first = NULL, last = NULL, count = 0;
linkedListType(const linkedListType<Type>& otherList);
//copy constructor
~linkedListType();
//destructor
//Deletes all the nodes from the list.
//Postcondition: The list object is destroyed.
void deleteElement(const Type& uLink);
//Delete a user specified element from
//the linked list.
protected:
int count; //variable to store the number of list elements
//
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 == NULL);
}
template <class Type>
linkedListType<Type>::linkedListType() //default constructor
{
first = NULL;
last = NULL;
count = 0;
}
template <class Type>
void linkedListType<Type>::destroyList()
{
nodeType<Type> *temp; //pointer to deallocate the memory
//occupied by the node
while (first != NULL) //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 = NULL; //initialize last to NULL; first has already
//been set to NULL 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 != NULL) //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 != NULL);
return first->info; //return the info of the first node
}//end front
template <class Type>
Type linkedListType<Type>::back() const
{
assert(last != NULL);
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(NULL);
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 != NULL) //if the list is nonempty, make it empty
destroyList();
if (otherList.first == NULL) //otherList is empty
{
first = NULL;
last = NULL;
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 = NULL; //set the link field of
//the node to NULL
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 != NULL)
{
newNode = new nodeType<Type>; //create a node
newNode->info = current->info; //copy the info
newNode->link = NULL; //set the link of
//newNode to NULL
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 = NULL;
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;
}
template <class Type>
void linkedListType<Type>::deleteElement(const Type& uLink)
{
int iCount=0;
for (int i=*first; i!=*last; i++; iCount++)
if(uLink==iCount)
{
this->erase(i);
break;
}
if(uLink!=iCount)
{
cerr<<"The specified element is not in the list."<<endl;
}
}
#endifHeader orderedLinkedList.h
#ifndef H_orderedListType
#define H_orderedListType
//***********************************************************
// Author: D.S. Malik
//
// This class specifies the members to implement the basic
// properties of an ordered doubly linked list.
//***********************************************************
#include "linkedList.h"
using namespace std;
template <class Type>
class orderedLinkedList: 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 insert(const Type& newItem);
//Function to insert newItem in the list.
//Postcondition: first points to the new list, newItem
// is inserted at the proper place in the list, and
// count is incremented by 1.
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
// of the new list, and count is decremented by 1. If
// deleteItem is not in the list, an appropriate message
// is printed.
};
template <class Type>
bool orderedLinkedList<Type>::search(const Type& searchItem) const
{
bool found = false;
nodeType<Type> *current; //pointer to traverse the list
current = first; //start the search at the first node
while (current != NULL && !found)
if (current->info >= searchItem)
found = true;
else
current = current->link;
if (found)
found = (current->info == searchItem); //test for equality
return found;
}//end search
template <class Type>
void orderedLinkedList<Type>::insert(const Type& newItem)
{
nodeType<Type> *current; //pointer to traverse the list
nodeType<Type> *trailCurrent; //pointer just before current
nodeType<Type> *newNode; //pointer to create a node
bool inList = false;
bool found;
newNode = new nodeType<Type>; //create the node
newNode->info = newItem; //store newItem in the node
newNode->link = NULL; //set the link field of the node
//to NULL
if (first == NULL) //Case 1
{
first = newNode;
last = newNode;
count++;
}
else
{
current=first;
while (current!=NULL || inList!=true)
{
if(current->info == newItem)
{
inList=true;
}
else
{
current=current->link;
}
}
if(inList==false)
{
current = first;
found = false;
while (current != NULL && !found) //search the list
{
if (current->info >= newItem)
{
found = true;
}
else
{
trailCurrent = current;
current = current->link;
}
}
if (current == first) //Case 2
{
newNode->link = first;
first = newNode;
count++;
}
else //Case 3
{
trailCurrent->link = newNode;
newNode->link = current;
if (current == NULL)
{
last = newNode;
}
count++;
}
}
else
cerr<<"Item is already in the list."<<endl;
}
}
template<class Type>
void orderedLinkedList<Type>::insertFirst(const Type& newItem)
{
insert(newItem);
}//end insertFirst
template<class Type>
void orderedLinkedList<Type>::insertLast(const Type& newItem)
{
insert(newItem);
}//end insertLast
template<class Type>
void orderedLinkedList<Type>::deleteNode(const Type& deleteItem)
{
nodeType<Type> *current; //pointer to traverse the list
nodeType<Type> *trailCurrent; //pointer just before current
bool found;
if (first == NULL) //Case 1
cout << "Cannot delete from an empty list." << endl;
else
{
current = first;
found = false;
while (current != NULL && !found) //search the list
if (current->info >= deleteItem)
found = true;
else
{
trailCurrent = current;
current = current->link;
}
if (current == NULL) //Case 4
cout << "The item to be deleted is not in the "
<< "list." << endl;
else
if (current->info == deleteItem) //the item to be
//deleted is in the list
{
if (first == current) //Case 2
{
first = first->link;
if (first == NULL)
last = NULL;
delete current;
}
else //Case 3
{
trailCurrent->link = current->link;
if (current == last)
last = trailCurrent;
delete current;
}
count--;
}
else //Case 4
cout << "The item to be deleted is not in the "
<< "list." << endl;
}
}//end deleteNode
#endifTest File
//**********************************************************
// Author: D.S. Malik
//
// This program tests the various operations on an ordered
// linked list.
//**********************************************************
#include <iostream> //Line 1
#include "orderedLinkedList.h" //Line 2
using namespace std; //Line 3
int main() //Line 4
{
orderedLinkedList<int> list1; //Line 5
int num; //Line 6
cout << "Line 7: Enter numbers ending "
<< "with -999." << endl; //Line 7
cin >> num; //Line 8
while (num != -999) //Line 9
{ //Line 10
list1.insert(num); //Line 11
cin >> num; //Line 12
} //Line 13
cout << endl; //Line 14
cout << "Line 15: list1: "; //Line 15
list1.print(); //Line 16
cout << endl; //Line 17
cout<<"Enter a number to be inserted: ";
cin>>num;
list1.insert(num);
cout<<endl;
cout << "Line 15: list1: "; //Line 15
list1.print(); //Line 16
cout << endl;
int x=0;
cout<<endl;
cout<<"End(1 for yes)? "<<endl;
cin>>x;
if(x==1)
exit(0);
return 0; //Line 29
} //Line 30