Data Structures - Inserting, deleting and displaying elements in the Double Circular Linked List

  #include< iostream.h >
  #include< conio.h >
  class cirdlink
  {
     struct node
     {
       int data;
       node *rnext;
       node *lnext;
     }*new1,*head,*tail,*ptr,*temp;
     public:
     cirdlink()
     {
       head=tail=NULL;
     }
     void creation();
     void insertion();
     void deletion();
     void display();
   };
   void cirdlink :: creation()
   {
     if(head==NULL)
     {
       new1=new node[sizeof(node)];
       new1->rnext=NULL;
       new1->lnext=NULL;
       cout<<"enter student number :";
       cin>>new1->data;
       head=new1;
       tail=new1;
       head->rnext=tail;
       head->lnext=tail;
       tail->rnext=head;
       tail->lnext=head;
     }
     else
       cout<<" creation done only once !";
   }
   void cirdlink :: insertion()
   {
     int i,pos;
     new1=new node[sizeof(node)];
     new1->rnext=NULL;
     new1->lnext=NULL;
     cout<<"enter student number :";
     cin>>new1->data;
     cout<<"enter position you want to insert :";
     cin>>pos;
     if(pos==1)
     {
       new1->rnext=head;
       head=new1;
       tail->lnext=head;
       tail->rnext=head;
       head->lnext=tail;
     }
     else
     {
       i=1;
       temp=head;
       while(i < pos-1 && temp->rnext!=tail)
       {
         i++;
         temp=temp->rnext;
       }
       if(temp->rnext==tail)
       {
         new1->rnext=tail->rnext;
         tail->rnext=new1;
         new1->lnext=tail;
         tail=new1;
         head->lnext=tail;
       }
       else
       {
         new1->rnext=temp->rnext;
         new1->lnext=temp;
         temp->rnext=new1;
         new1->rnext->lnext=new1;
       }
     }
   }
   void cirdlink :: deletion()
   {
     int pos,i;
     cout<<"Enter Position you want to Delete ?";
     cin>>pos;
     if(pos==1 && head!=tail)
     {
       ptr=head;
       head=head->rnext;
       head->lnext=tail;
       tail->rnext=head;
       delete ptr;
     }
     else
     {
       i=1;
       temp=head;
       while(i < pos-1 && temp->rnext!=tail)
       {
         i++;
         temp=temp->rnext;
       }
       if(temp->rnext!=tail)
       {
         ptr=temp->rnext;
         temp->rnext=ptr->rnext;
         ptr->rnext->lnext=ptr->lnext;
         delete ptr;
       }
       else
       {
         if(temp->rnext==tail && head!=tail)
         {
           ptr=tail;
           tail=temp;
           tail->rnext=head;
           head->lnext=tail;
           delete ptr;
         }
         else
         {
           head=NULL;
           tail=NULL;
           delete head;
           delete tail;
         }
       }
     }
   }
   void cirdlink::display()
   {
     int ch;
     cout<<"1.forward
     2.backward:";
     cout<<"Enter your choice<1/2>?";
     cin>>ch;
     switch(ch)
     {
       case 1: if(head!=NULL)
       {
         temp=head;
         while(temp!=tail)
         {
           cout<< temp->data<<" ";
           temp=temp->rnext;
         }
         if(temp==tail)
           cout<< temp->data;
       }
       break;
       case 2 : if(tail!=NULL)
       {
         temp=tail;
         while(temp!=head)
         {
           cout<< temp->data<<" ";
           temp=temp->lnext;
         }
         if(temp==head)
           cout<< temp->data;
       }
       break;
     }
   }
   void main()
   {
     cirdlink c1;
     int ch;
     char op;
     do
     {
       clrscr();
       cout<<"----------Menu------------";
       cout<<" 1.Creation
       2.Insertion
       3.Deletion
       4.Display ";
       cout<<"Enter Your choice <1..4> ?";
       cin>>ch;
       switch(ch)
       {
         case 1 : c1.creation();
           break;
         case 2 : c1.insertion();
           break;
         case 3 : c1.deletion();
           break;
         case 4 : c1.display();
           break;
       }
       cout<<"Do you want to continue < Y/N > ?";
       cin>>op;
     }while(op=='y' || op=='Y');
     getch();
   }