The document contains a C++ implementation of a doubly linked list with functions for inserting nodes at different positions, displaying the list, searching for a value, and deleting nodes. Key operations include 'insertfront', 'insertafter', 'insertend', 'deletefirstnode', 'deletespecific', and 'deleteendnode'. The main function demonstrates the functionality by inserting and displaying nodes.

1. #include<iostream>
using namespace std;
struct DLL
{
int data;
DLL *next;
DLL *prev;
}*head=NULL;
void insertFront (int data);
void insertAfter (DLL* prevNode, int data);
void insertEnd (int data);
void displayList();
bool search(int x);
void DeleteFirstNode();
void DeleteSpecific(int val);
void DeleteEndNode ();
int main()
{
insertFront(5);
insertEnd(50);
insertFront(8);
insertFront(10);
insertAfter(head->next->next, 100);
//displayList();
//DeleteFirstNode();
displayList();
//DeleteEndNode();
//DeleteSpecific(8);
//displayList();
//search(10)?cout <<"Found"<<endl: cout<< "Not Found"<<endl;
}
void insertFront (int data)
{
DLL *newNode = new DLL;
newNode->data = data;
newNode->next = head;
newNode->prev = NULL;
if(head != NULL)
{
head->prev = newNode;
}
head = newNode;
}
void insertAfter (DLL* prevNode, int data)
{
if (prevNode == NULL)
{
cout<<"Previous node is required , it cannot be NULL";
}

2. DLL *newNode = new DLL;
newNode->data = data;
newNode->next = prevNode->next;
prevNode->next = newNode;
newNode->prev = prevNode;
if(newNode->next != NULL)
{
newNode->next->prev = newNode;
}
}
void insertEnd (int data)
{
DLL *newNode = new DLL;
DLL *last = head;
newNode->data = data;
newNode->next = NULL;
if (head == NULL)
{
newNode->prev = NULL;
head = newNode;
}
while (last->next != NULL)
{last = last->next;}
last->next = newNode;
newNode->prev = last;
}
void displayList()
{
DLL* last= head;
while (last != NULL)
{
cout<<last->data<<endl;
last = last->next;
}
}
bool search(int x)
{
DLL* temp = head;
while (temp->data != x
&& temp->next != NULL)

3. {
temp = temp->next;
}
if (temp->data != x)
{
return false;
}
return true;
}
void DeleteFirstNode()
{
DLL *temp = head;
if(head == NULL)
{
cout << "n List is emptyn";
}
else
{
head = head -> next;
head -> prev = NULL;
free(temp);
cout <<"nNode Deletedn";
}
}
void DeleteSpecific(int val)
{
DLL *temp = head;
DLL *ptr = new DLL;
while(temp -> data != val)
temp = temp -> next;
if(temp -> next == NULL)
{
cout<<("nCan't deleten");
}
else
{
temp->next->prev = temp->prev;
temp->prev->next = temp->next;
//ptr = temp -> next;
//temp -> next = ptr -> next;
//ptr -> next -> prev = temp;
free(ptr);
cout <<("nNode Deletedn");
}
}
void DeleteEndNode ()
{
DLL *temp = head;

4. if(head == NULL)
{
cout <<"The list is empty";
}
else
{
while(temp->next != NULL)
{
temp = temp -> next;
}
temp -> prev -> next = NULL;
free(temp);
cout <<"nNode Deletedn";
}
}