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(); 

}