Chapter 3, Problem 8R

Explanation of Solution

Program code:

//include the required header files

#include<iostream>

#include<cstdio>

#include<cstdlib>

/* Node Declaration*/

using namespace std;

//create a structure

struct node

{

//structure members

int info;

struct node *next;

struct node *prev;

}*start;

/*Class Declaration */

class double_llist

{

//public access modifier

public:

//declare the member functions

void create_list(int value);

void add_begin(int value);

void add_after(int value, int position);

void delete_element(int value);

void search_element(int value);

void display_dlist();

void count();

void reverse();

//define a method

double_llist()

{

//set the value of start

start = NULL;

}

};

/* Main*/

int main()

{

//declare the required variables

int choice, element, position;

double_llist dl;

//iterate a while loop

while (1)

{

//display the choices

cout<<endl<<"----------------------------"<<endl;

cout<<endl<<"Operations on Doubly linked list"<<endl;

cout<<endl<<"----------------------------"<<endl;      

cout<<"1.Create Node"<<endl;

cout<<"2.Add at begining"<<endl;

cout<<"3.Add after position"<<endl;

cout<<"4.Delete"<<endl;

cout<<"5.Display"<<endl;

cout<<"6.Count"<<endl;

cout<<"7.Reverse"<<endl;

cout<<"8.Quit"<<endl;

//prompt the user to enter the choice

cout<<"Enter your choice : ";

cin>>choice;

//switch cases

switch ( choice )

{

//case 1

case 1:

//prompt the user to enter the element

cout<<"Enter the element: ";

//scan for the value

cin>>element;

//call the method create_list(element)

dl.create_list(element);

//new line

cout<<endl;

//break fron the case

break;

case 2:

//prompt the user to enter the element

cout<<"Enter the element: ";

//scan for the value

cin>>element;

//call the method add_begin(element)

dl.add_begin(element);

//new line

cout<<endl;

//break fron the case

break;

case 3:

//prompt the user to enter the element

cout<<"Enter the element: ";

//scan for the value

cin>>element;

//prompt the user to enter the position

cout<<"Insert Element after postion: ";

cin>>position;

//call the method add_after(element)

dl.add_after(element, position);

//new line

cout<<endl;

//break fron the case

break;

case 4:

//if the condition is true

if (start == NULL)

{

//print the statement

cout<<"List empty,nothing to delete"<<endl;

//break fron the condition

break;

}

//prompt the user to enter the element

cout<<"Enter the element for deletion: ";

//scan for the value

cin>>element;

//call the method delete_element(element)

dl.delete_element(element);

//new line

cout<<endl;

//break fron the case

break;

case 5:

//call the method display_dlist(element)

dl.display_dlist();

//new line

cout<<endl;

//break fron the case

break;

case 6:

//call the method count(element)

dl.count();

//break fron the case

break;

case 7:

//if the condition is true

if (start == NULL)

{

//print the statement

cout<<"List empty,nothing to reverse"<<endl;

//break fron the condititon

break;

}

//call the method reverse(element)

dl.reverse();

//new line

cout<<endl;

//break fron the case

break;

case 8:

//exit from while loop

exit(1);

default:

//print the statement

cout<<"Wrong choice"<<endl;

}

}

//return zero

    return 0;

}

/* Create Double Link List*/

void double_llist::create_list(int value)

{

//create struct vaiable

struct node *s, *temp;

//set the value of temp

temp = new(struct node);

//insert the value

temp->info = value;

//set next as Null

temp->next = NULL;

//if the condition is true

if (start == NULL)

{

//set prev equal to Null

temp->prev = NULL;

//set start equal to temp

start = temp;

}

else

{

    //set s equal to start

s = start;

//iterate a while loop

while (s->next != NULL)

//assign the value

s = s->next;

s->next = temp;

temp->prev = s;

}

}

/* Insertion at the beginning */

void double_llist::add_begin(int value)

{

//if the condition is true

if (start == NULL)

{

//print the statement

cout<<"First Create the list."<<endl;

return;

}

//inserting the element

struct node *temp;

temp = new(struct node);

temp->prev = NULL;

temp->info = value;

temp->next = start;

start->prev = temp;

start = temp;

cout<<"Element Inserted"<<endl;

}

/* Insertion of element at a particular position*/

void double_llist::add_after(int value, int pos)

{

//if the condition is true

if (start == NULL)

{

//print the statement

cout<<"First Create the list."<<endl;

//return

return;

}

//create struct variables

struct node *tmp, *q;

//create the required variables

int i;

q = start;

//iterate a for loop

for (i = 0;i < pos - 1;i++)

{

//set the value of q

q = q->next;

//if the value of q equal to null

if (q == NULL)

{

//print the statement

cout<<"There are less than ";

cout<<pos<<" elements...