Computer Science Question: link list c++...declaring reverse function

buzz1

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Date Posted: 7/23/2008 1:41:33 AM Status: Closed

link list c++...declaring reverse function

Course	Textbook	Chapter	Problem
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Question Details:

I have my code just need to add the reverse function to it.

Declare the reverse function as follow:
void reverse();

The function reverses the order of the nodes held by the linked list. This function can be implemented in several ways. The easiest way is to create a new linked list with the values from the original linked list (in reverse order). Then you could substitute the new list for the old list with a statement like
head = newList;
It is more challenging to reverse the list "in place" without creating any new nodes.
Change main.cpp to reverse the list and the display the reversed list.

Main.cpp
#include <iostream>
#include <fstream>
#include <iomanip>
#include <string>
#include "part1.h"

using namespace std;

int main()
{
   char name;
   ifstream infile;
   infile.open("demoTest.txt");
   part1 list;

if(!infile)
   cout << "Can not open file" << endl;
else
{
   infile >> name;

   while(infile)
   {
       list.insertNode(name);
       infile >> name;
   }

   cout << "The list now contains:" << endl;
   list.displayList();
   list.~part1();
}
   return 0;
}

Part1.cpp#include "part1.h"
#include <iostream>
#include <fstream>
using namespace std;

void part1::appendList(char num)
{
   listNode *newNode;
   listNode *nodePtr;

   newNode = new listNode;
   newNode->letter = num;
   newNode->next = NULL;

   if(!head)
       head = newNode;
   else
   {
       nodePtr = head;

       while(nodePtr->next)
           nodePtr = nodePtr->next;

       nodePtr->next = newNode;
   }
}

void part1::displayList() const
{
   listNode *nodePtr; // move through the list

   nodePtr = head; //position nodePtr at head of the list

   while(nodePtr)
   {
       cout << nodePtr->letter << endl;//display value

       nodePtr = nodePtr->next;//move to next node
   }
}

void part1::insertNode(char num)
{
   // get a new node to insert
   listNode *newNode;
   listNode *nodePtr; // to traverse the list
    listNode *previousNode = NULL; // the previous node
   // allocate a new node
   newNode= new listNode;
   newNode->letter=num;

   if(!head)
   {
       head = newNode;
        newNode->next=NULL;
   }
   else
   {
       nodePtr = head;
       previousNode= NULL;

      while ( nodePtr!=NULL && toupper(nodePtr->letter) <= toupper (num))
      {
         if (nodePtr->letter >num&&toupper (nodePtr->letter) == toupper (num))   //current is the last in list
         {
               break;
         }
              previousNode = nodePtr;
              nodePtr=nodePtr->next;

      }
       if(previousNode ==NULL)
       {
           head=newNode;
           newNode->next=nodePtr;
       }
       else
       {
           previousNode->next=newNode;
           newNode->next=nodePtr;
       }

      }

   }

part1::~part1()
{
   cout << "\nDeleting the list\n" << endl;
   do
   {
       listNode *nodePtr=head;
       cout << "Delete element " << nodePtr->letter << endl;
       head=head->next; //move to next
       delete nodePtr; //delete the node
   }while(head!=NULL);

   cout << "\nDeletion complete" << endl;
} // end

Part1.h
#ifndef PART1_H
#define PART1_H
#include <iostream>
using namespace std;

class part1
{
public:
   part1()
   {
       head = NULL;
   }
   void appendList(char);
   void insertNode(char);
   void displayList() const;
   ~part1();

private:
   struct listNode
   {
       char letter;
       struct listNode *next;
   };
   listNode *head;

};
#endif

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link list c++...declaring reverse function

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