DOUBLE LINK LIST

#include <iostream.h>

class node

{

public:

int value;           //value stored in the node

node *next;          //pointer to next node

node *prev;          //pointer to previous node

};

class dlist

{

public:

node *front;       //pointer to front of list  

node *back;        //pointer to back of list 

dlist()

{

front=NULL;

back=NULL;

}

void insertFront(int value);            

void insertBack(int value);

void removeFront();

void removeBack();

void insertBefore(int value,node *nodeB);

void insertAfter(int value,node *nodeA);

void removeBefore(node *nodeB);

void removeAfter(node *nodeA);

void removeNode(node *newNode);

void printDListFront();

void printDListBack();

};

//insert a node before nodeB

void dlist::insertBefore(int value,node *nodeB)   

{

node *newNode;

newNode=new node();

newNode->prev=nodeB->prev;

newNode->next =nodeB;

newNode->value =value;

if(nodeB->prev==NULL)

{

this->front=newNode;

}

nodeB->prev=newNode;

}

//insert a node before the front node

void dlist::insertFront (int value)

{

node *newNode;

if(this->front==NULL)

{

newNode=new node();

this->front=newNode;

this->back =newNode;

newNode->prev=NULL;

newNode->next=NULL;

newNode->value=value;

}

else

{

insertBefore(value,this->front );

}

}

//insert a node after  nodeB

void dlist::insertAfter(int value,node *nodeB)

{

node *newNode;

newNode=new node();

newNode->next= nodeB->next ;

newNode->prev  =nodeB;

newNode->value =value;

if(nodeB->next==NULL)

{

cout<<"\n "<< endl;

this->back =newNode;

}

nodeB->next=newNode;

cout<<"2"<<endl;

}

//insert a node after the last node

void dlist::insertBack (int value)

{         

if(this->back==NULL)

{

cout<<"insert at back";

insertFront(value);

}

else

{

cout<<"insert at back";

insertAfter(value,this->back  );

}

}

//remove the front node

void dlist::removeFront ()

{

removeNode(this->front);

}

//remove a back node

void dlist::removeBack  ()

{

removeNode(this->back);

}

//remove before a node

void dlist::removeBefore(node *nodeB)

{

if(nodeB->prev==this->front)

{

this->front=nodeB;

this->front->prev=NULL;

}

else

{

removeNode(nodeB->prev);

}

}

//remove after a node

void dlist::removeAfter(node *nodeA)

{

if(nodeA->next==this->back)

{

this->back=nodeA;

this->back->next=NULL;

}

else

{

removeNode(nodeA->next);

}

}

//remove a perticular node

void dlist::removeNode(node *nodeToRemove)

{

if(nodeToRemove==this->front)

{

this->front=this->front->next;

this->front->prev=NULL;

}

else if (nodeToRemove==this->back)

{

this->back=this->back->prev;

this->back->next=NULL ;

}

else

{

nodeToRemove->prev->next=nodeToRemove->next;

nodeToRemove->next->prev=nodeToRemove->prev;

}

}

//Print the list from front

void dlist::printDListFront()

{

node* curr2;

curr2= this->front;

cout<<"\n-----\n";

cout<<"Queue\n";

cout<<"-----\n";

//cout<<"size:"<<getQueueSize()<<endl;

while(curr2!=NULL)

{

cout<<" |"<<curr2->value<<"|";

curr2=curr2->next;

}

cout<<endl;

}// print the Double Linked List from front

// print the Double Linked List from backwards

void dlist::printDListBack()

{

node* curr2;

curr2= this->back;

cout<<"\n-----\n";

cout<<"Queue\n";

cout<<"-----\n";

//cout<<"size:"<<getQueueSize()<<endl;

while(curr2!=NULL)

{

cout<<" |"<<curr2->value<<"|";

curr2=curr2->prev;

}

cout<<endl;

}// print the Double Linked List from back

void main()

{

dlist *st ;

st= new dlist();

st->insertBack(8);

st->printDListFront ();

st->insertBack(5);

st->printDListFront ();

st->insertBack(6);

st->printDListFront ();

st->insertFront(1) ;

st->printDListFront ();

st->insertFront(3) ;

st->printDListFront ();

st->insertBack(7);

st->printDListFront ();

st->removeFront();

st->printDListFront ();

st->removeBack();

st->printDListFront ();

}

#include
using namespace std;
class A
{
struct node
{
int data;
struct node *next,*prev;
}*start;
public: A()
{
start=NULL;
}
void insert(int n);
void show();
void del();
};
void A::insert(int n)
{
node *temp1,*temp2;
if(start==NULL)
{
start=new node;
start->data=n;
start->next=start->prev=NULL;
}
else
{
temp1=start;
while(temp1->next!=NULL)
temp1=temp1->next;
temp2=new node;
temp2->data=n;
temp2->next=NULL;
temp2->prev=temp1;
temp1->next=temp2;
}
}
void A::del()
{
node *temp;
temp=start;
start=start->next;
delete temp;
}
void A::show()
{
node *temp;
temp=start;
while(temp!=NULL)
{
cout<data<<" ";
temp=temp->next;
}
cout<<"\n\n";
}
int main()
{
int n,ch;
A a;
cout<<"Enter your choice "<>ch;
while(1)
{
switch(ch)
{
case 1: cout<<"Enter the element ";
cin>>n;
a.insert(n);
break;
case 2: cout<<"After delete the elements are ";
a.del();
a.show();
break;
case 3: cout<<"The elements are ";
a.show();
break;
case 4: return 0;
}
cout<<"\n1.Insert\n2.Delete\n3.Display\n4.Exit\n";
cin>>ch;
}
system("pause");
}