Insertion node at particular position

Insertion node at particular position:

//insert
#include<stdio.h>
#include<iostream.h>
#include<conio.h>
template<class T>
class node
{
 node<T> *llink;
 T data;
 node<T> *rlink;
 friend class dll<T>;
};
template <class T>
class dll
{
 private:
        node<T> *l,*r;
 public:
        dll();
       ~dll();
int isempty()        ;
        void display();
        int length();
        void insert(int i, T x);
        
        


};
template<class T>
dll<T>::dll()
{
 l=r=NULL;
}
template<class T>
int dll<T>::isempty()
{
 return(l==NULL);
}
template<class T>
void dll<T>::display()
{

 node<T> *p;
 if(isempty())
 {
  cout<<"DLL is empty\n";
 }
 else
 {
   cout<<"DLL is as follows\n";
   for(p=l;p!=NULL;p=p->rlink)
     cout<<p->llink<<"\t"<<p->data<<"\t"<<p->rlink<<"\n";
 }
}
//length()
template<class T>
int dll<T>::length()
{
 int ctr=0;
 node<T> *p;
 p=l;
 while(p!=NULL)
 {
  ctr++;
  p=p->rlink;
 }
 return(ctr);
}
   //insert()

template<class T>
void dll<T>::insert(int i,T x)
{
 node<T> *temp,*p,*next;
 if(i<0||i>length())
  cout<<"Non existing node\n";
 else
 {
  p=new node<T>;
  p->data=x;
  if(isempty())
  {
   l=r=p;
   p->llink=p->rlink=NULL;
  }
  else if(i==0)
  {
   l->llink=p;
   p->rlink=l;
   p->llink=NULL;
   l=p;
  }
  else if(i==length())
  {
   p->rlink=NULL;
   p->llink=r;
   r->rlink=p;
   r=p;
  }
  else
  {
   temp=l;
   for(int j=1;j<=i-1;j++)
    temp=temp->rlink;
   next=temp->rlink;
   p->llink=temp;
   p->rlink=next;
   next->llink=p;
  }
 }
}
template<class T>
dll<T>::~dll()
{
}

main()
{
 dll<int>a;
 node<int>*p;
 int ch,i,x;
 clrscr();
 cout<<"enter value of i( 0 to insert ar the beginning)\n";
 cin>>i;
 cout<<"enter value of new node\n";
 cin>>x;
 a.insert(i,x);
          a.display();
 getch();
return(0);

}//main()
Doubly Linked List Operations

Types of Linked list

1.     Single Linked List

2.    Doubly Linked List

3.    Circular Linked List 

Programs on Doubly Linked List

Node class structures