So I decided it was time for me to learn linked list and boy oh boy I never thought I would be in for such a treat. In order to do this I have been following through a chapter in a book and trying to fill in things as I go along. I have made it pretty fat and am grasping a lot of things but there is still one major problem I am having. Funny thing is it mostly does not have to do with Linked List themselevs. Anyways I am trying to write two functions one to display the n'th node in a list and another to delete the n'th node in the list (n'th being a number the user inputs). So for example say the user wants to delete the 9th node in the list. The function will traverse the list until it reaches the 9th node and delete it. I think I have to use a for loop and then set a pointer to the current node but I am just not sure.

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I am posting a hefty amount of code. I have commented out the two functions I am still trying to figure out with three lines worth of //////. The only reason why I am posting so much code is because I feel like the it is essential to anyone who is willing to help me. If it is not please let me know so I can shorten it.

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Anyways if anyone would like to have a stab at it or and let me know what your thoughts are that would be great.

If there is anyway I can make this mor legiable let me know...

Code:using#ifndef H_LinkedListType #define H_LinkedListType #include "stdafx.h" #using <mscorlib.dll> #include <iostream> #include <cassert> using namespace std; template <class Type> struct nodeType { Type info; nodeType<Type> *link; }; template<class Type> class linkedListType { friend ostream& operator<<(ostream&, const linkedListType<Type>&); public: const linkedListType<Type>& operator= (const linkedListType<Type>&); //Overload the assignment operator. void initializeList(); //Initializes the list to an empty state. //Postcondition: first = NULL, last = NULL, // count = 0 bool isEmptyList(); //Function to determine whether the list is empty. //Postcondition: Returns true if the list is empty; // otherwise, returns false. int length(); //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(); //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, then the // program terminates; otherwise, // the first element of the list is // returned. Type back(); //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, then the // program terminates; otherwise, // the last element of the list is // returned. bool search(const Type& searchItem); //Function to determine whether searchItem is in //the list. //Postcondition: Returns true if searchItem is found // in the list; otherwise, it returns // false. void insertFirst(const Type& newItem); //Function to insert newItem in the list. //Postcondition: first points to the new list // and newItem is inserted at the // beginning of the list. void insertLast(const Type& newItem); //Function to return newItem at the end of the //list. //Postcondition: first points to the new list, // newItem is inserted at the end // of the list, and last points to // the last node in the list. 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, and last points to the last // node of the updated list. ////////////////////////////////////////////////////////////////// ///////////////////////////////H E L P /////////////////////////// ////////////////////////////////////////////////////////////////// Type getKThElement(int k); //Function to search list for the n'th node in the list //Postcondition: When found display info void deteteKthElement(int k); //Function used to delete the n'th number node in the list ////////////////////////////////////////////////////////////////// ////////////////////////////////////////////////////////////////// ////////////////////////////////////////////////////////////////// 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. 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() { 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 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> int linkedListType<Type>::length() { return count; } // end length template<class Type> Type linkedListType<Type>::front() { assert(first != NULL); return first->info; //return the info of the first node }//end front template<class Type> Type linkedListType<Type>::back() { assert(last != NULL); return last->info; //return the info of the first node }//end back template<class Type> bool linkedListType<Type>::search(const Type& searchItem) { nodeType<Type> *current; //pointer to traverse the list bool found; current = first; //set current to point to the //first node in the list found = false; //set found to false while(current != NULL && !found) //search the list if(current->info == searchItem) //item is found found = true; else current = current->link; //make current point //to the next node return found; }//end search ///////////////////////////////////////////////////////////////// /////////////////////////////H E L P///////////////////////////// ///////////////////////////////////////////////////////////////// template<class Type> Type getKThElement(int k) { // User enters a number // Traverse list until you have reached users number (for loop?) // Display result } ///////////////////////////////////////////////////////////////// ///////////////////////////////////////////////////////////////// ///////////////////////////////////////////////////////////////// template<class Type> void linkedListType<Type>::insertFirst(const Type& newItem) { nodeType<Type> *newNode; //pointer to create the new node newNode = new nodeType<Type>; //create the new node assert(newNode != NULL); //If unable to allocate memory, //terminate the program newNode->info = newItem; //store the new item in the node newNode->link = first; //insert newNode before first first = newNode; //make first point to the //actual first node count++; //increment count if(last == NULL) //if the list was empty, newNode is also //the last node in the list last = newNode; } template<class Type> void linkedListType<Type>::insertLast(const Type& newItem) { nodeType<Type> *newNode; //pointer to create the new node newNode = new nodeType<Type>; //create the new node assert(newNode != NULL); //If unable to allocate memory, //terminate the program newNode->info = newItem; //store the new item in the node newNode->link = NULL; //set the link field of newNode //to NULL if(first == NULL) //if the list is empty, newNode is //both the first and last node { first = newNode; last = newNode; count++; //increment count } else //the list is not empty, insert newNode after last { last->link = newNode; //insert newNode after last last = newNode; //make last point to the actual last node count++; //increment count } }//end insertLast //////////////////////////////////////////////////////////////////// /////////////////////////////////H E L P//////////////////////////// //////////////////////////////////////////////////////////////////// void deteteKthElement(int k) { //User enters number //Traverse list until you reach that node //Delete node } //////////////////////////////////////////////////////////////////// //////////////////////////////////////////////////////////////////// //////////////////////////////////////////////////////////////////// template<class Type> void linkedListType<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; list is empty. cerr<<"Can not delete from an empty list.\n"; else { if(first->info == deleteItem) //Case 2 { current = first; first = first->link; count--; if(first == NULL) //list had only one node last = NULL; delete current; } else //search the list for the node with the given info { found = false; trailCurrent = first; //set trailCurrent to point to //the first node current = first->link; //set current to point to the //second node while((!found) && (current != NULL)) { 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; count--; if(last == current) //node to be deleted was //the last node last = trailCurrent; //update the value of last delete current; //delete the node from the list } else cout<<"Item to be deleted is not in the list."<<endl; } //end else } //end else } //end deleteNode //Overloading the stream insertion operator template<class Type> ostream& operator<<(ostream& osObject, const linkedListType<Type>& list) { nodeType<Type> *current; //pointer to traverse the list current = list.first; //set current so that it points to //the first node while(current != NULL) //while more data to print { osObject<<current->info<<" "; current = current->link; } return osObject; } template<class Type> linkedListType<Type>::~linkedListType() // destructor { destroyList(); }//end destructor 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 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 assert(first != NULL); 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 assert(newNode!= NULL); 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 //copy constructor 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; } int _tmain() { return 0; }

Thanks

Chad