Searching the data in the Doubly linked list

//searching
#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();
     
node<T>* search(T x);
void append(node<T>*k);
void create();
};
template<class T>
dll<T>::dll()
{
 l=r=NULL;
}
template<class T>
int dll<T>::isempty()
{
 return(l==NULL);
}

//search()
template<class T>
node<T>* dll<T>::search(T x)
{
 node<T> *p;
 p=l;
 while(p!=NULL)
 {
 if(p->data==x)
  return(p);
 }
 return(NULL);
}
//apend()
template<class T>
void dll<T>::append(node<T>* k)
{
 node<T> *last;
 k->rlink=NULL;
 if(isempty())
   l=r=k;
 else
 {
   //last=r;
   last=l;
   while(last->rlink!=NULL)
   {
    last=last->rlink;
   }
   last->rlink=k;
   r=last;
  }
}
//create()
template<class T>
void dll<T>::create()
{
  T x;
  node<T> *k;
  l=r=NULL;
  cout<<"enter values terminated by -1 or !\n";
  cin>>x;
  while(x!=-1&&x!='!')
  {
   k=new node<T>;
   k->data=x;
   append(k);
   cin>>x;
   r=r->rlink;
  }
 }//create()

template<class T>
dll<T>::~dll()
{

}
main()
{
 dll<int>a;
 node<int>*p;
 int ch,i,x;
 clrscr();
 a.create();
 cout<<"enter value to be searched\n";
 cin>>x;
 p=a.search(x);
 if(p==NULL)
  cout<<"It is not found\n";
 else
  cout<<"it is found at address="<<p<<"\n";

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

Some terminology of Doubly Linked List programs