C++ -- Implement a doubly linked list class with the following functions: insert
ID: 3832020 • Letter: C
Question
C++ -- Implement a doubly linked list class with the following functions: insert, delete, and display
I already have the following:
/*
* C++ Program to Implement Doubly Linked List
*/
#include<iostream>
#include<cstdio>
#include<cstdlib>
/*
* Node Declaration
*/
using namespace std;
struct node
{
int info;
struct node *next;
struct node *prev;
}*start;
/*
Class Declaration
*/
class double_llist
{
public:
void create_list(int value);
void add_after(int value, int position);
void delete_element(int value);
void display_dlist();
double_llist()
{
start = NULL;
}
};
/*
* Create Double Link List
*/
void double_llist::create_list(int value)
{
struct node *s, *temp;
temp = new(struct node);
temp->info = value;
temp->next = NULL;
if (start == NULL)
{
temp->prev = NULL;
start = temp;
}
else
{
s = start;
while (s->next != NULL)
s = s->next;
s->next = temp;
temp->prev = s;
}
}
/*
* Insertion of element at a particular position
*/
void double_llist::add_after(int value, int pos)
{
if (start == NULL)
{
cout<<"First Create the list."<<endl;
return;
}
struct node *tmp, *q;
int i;
q = start;
for (i = 0;i < pos - 1;i++)
{
q = q->next;
if (q == NULL)
{
cout<<"There are less than ";
cout<<pos<<" elements."<<endl;
return;
}
}
tmp = new(struct node);
tmp->info = value;
if (q->next == NULL)
{
q->next = tmp;
tmp->next = NULL;
tmp->prev = q;
}
else
{
tmp->next = q->next;
tmp->next->prev = tmp;
q->next = tmp;
tmp->prev = q;
}
cout<<"Element Inserted"<<endl;
}
/*
* Deletion of element from the list
*/
void double_llist::delete_element(int value)
{
struct node *tmp, *q;
/*first element deletion*/
if (start->info == value)
{
tmp = start;
start = start->next;
start->prev = NULL;
cout<<"Element Deleted"<<endl;
free(tmp);
return;
}
q = start;
while (q->next->next != NULL)
{
/*Element deleted in between*/
if (q->next->info == value)
{
tmp = q->next;
q->next = tmp->next;
tmp->next->prev = q;
cout<<"Element Deleted"<<endl;
free(tmp);
return;
}
q = q->next;
}
/*last element deleted*/
if (q->next->info == value)
{
tmp = q->next;
free(tmp);
q->next = NULL;
cout<<"Element Deleted"<<endl;
return;
}
cout<<"Element "<<value<<" not found"<<endl;
}
/*
* Display elements of Doubly Link List
*/
void double_llist::display_dlist()
{
struct node *q;
if (start == NULL)
{
cout<<"List empty,nothing to display"<<endl;
return;
}
q = start;
cout<<"The Doubly Link List is :"<<endl;
while (q != NULL)
{
cout<<q->info<<" <-> ";
q = q->next;
}
cout<<"NULL"<<endl;
}
Explanation / Answer
/*
* C++ Program to Implement Doubly Linked List
*/
#include<iostream>
#include<cstdio>
#include<cstdlib>
/*
* Node Declaration
*/
using namespace std;
struct node
{
int info;
struct node *next;
struct node *prev;
}*start;
/*
Class Declaration
*/
class double_llist
{
public:
void create_list(int value);
void add_after(int value, int position);
void delete_element(int value);
void display_dlist();
double_llist()
{
start = NULL;
}
};
/*
main
*/
int main()
{
int choice, element, position;
double_llist dl;
while (1)
{
cout<<endl<<"Operations to be done on Doubly linked list"<<endl;
cout<<"1.Create Node"<<endl;
cout<<"2.Add element after position"<<endl;
cout<<"3.Delete"<<endl;
cout<<"4.Display"<<endl;
cout<<"5.Quit"<<endl;
cout<<"Enter your choice : ";
cin>>choice;
switch ( choice )
{
case 1:
cout<<"Enter the element : ";
cin>>element;
dl.create_list(element);
cout<<endl;
break;
case 2:
cout<<"Enter the element: ";
cin>>element;
cout<<"Insert Element after postion: ";
cin>>position;
dl.add_after(element, position);
cout<<endl;
break;
case 3:
if (start == NULL)
{
cout<<"List empty,nothing to delete"<<endl;
break;
}
cout<<"Enter the element for deletion: ";
cin>>element;
dl.delete_element(element);
cout<<endl;
break;
case 4:
dl.display_dlist();
cout<<endl;
break;
case 5:
exit(1);
default:
cout<<"Wrong choice"<<endl;
}
}
return 0;
}
/*
* Create Double Link List
*/
void double_llist::create_list(int value)
{
struct node *s, *temp;
temp = new(struct node);
temp->info = value;
temp->next = NULL;
if (start == NULL)
{
temp->prev = NULL;
start = temp;
}
else
{
s = start;
while (s->next != NULL)
s = s->next;
s->next = temp;
temp->prev = s;
}
}
/*
* Insertion of element at a particular position
*/
void double_llist::add_after(int value, int pos)
{
if (start == NULL)
{
cout<<"First Create the list."<<endl;
return;
}
struct node *tmp, *q;
int i;
q = start;
for (i = 0;i < pos - 1;i++)
{
q = q->next;
if (q == NULL)
{
cout<<"There are less than ";
cout<<pos<<" elements."<<endl;
return;
}
}
tmp = new(struct node);
tmp->info = value;
if (q->next == NULL)
{
q->next = tmp;
tmp->next = NULL;
tmp->prev = q;
}
else
{
tmp->next = q->next;
tmp->next->prev = tmp;
q->next = tmp;
tmp->prev = q;
}
cout<<"Element Inserted"<<endl;
}
/*
* Deletion of element from the list
*/
void double_llist::delete_element(int value)
{
struct node *tmp, *q;
/*first element deletion*/
if (start->info == value)
{
tmp = start;
start = start->next;
start->prev = NULL;
cout<<"Element Deleted"<<endl;
free(tmp);
return;
}
q = start;
while (q->next->next != NULL)
{
/*Element deleted in between*/
if (q->next->info == value)
{
tmp = q->next;
q->next = tmp->next;
tmp->next->prev = q;
cout<<"Element Deleted"<<endl;
free(tmp);
return;
}
q = q->next;
}
/*last element deleted*/
if (q->next->info == value)
{
tmp = q->next;
free(tmp);
q->next = NULL;
cout<<"Element Deleted"<<endl;
return;
}
cout<<"Element "<<value<<" not found"<<endl;
}
/*
* Display elements of Doubly Link List
*/
void double_llist::display_dlist()
{
struct node *q;
if (start == NULL)
{
cout<<"List empty,nothing to display"<<endl;
return;
}
q = start;
cout<<"The Doubly Link List is :"<<endl;
while (q != NULL)
{
cout<<q->info<<" <-> ";
q = q->next;
}
cout<<"NULL"<<endl;
}
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