Circular Singly Linked List...

#include<iostream>
using namespace std;

class node
{
	public:
		int data;
		node *next;
		node()
		{
			data=0;
			next=0;
		}
		node(int value,node *n=0)
		{
			data=value;
			next=n;
		}
};

class link
{
	public:
		node *head;
		link()
		{
			head=0;
		}
		void insert_last()
		{
			int value;
			cout<<"Enter Value=";
			cin>>value;
			//node *n;
			if(head==0)
			{
				head=new node(value);
				head->next=head;
			}
			else
			{
				node *tmp;
				tmp=head;
				while(tmp->next!=head->next)
				{
					tmp=tmp->next;
				}
				tmp->next=new node(value);
				tmp->next->next=head;
			}
		}

		void insert_first()
		{
			int value;
			node *n;
			cout<<"Enter a value=";
			cin>>value;
			if(head==0)
			{
				n=new node(value);
				n->next=head;
				head=n;
			}
			else
			{
				head=new node(value,head);
			}
		}
		void insert_pos_before()
		{
			int value,pos;
			cout<<"Enter Position to Insert=";
			cin>>pos;
			cout<<"Enter Element=";
			cin>>value;
			node *tmp=head;
			node *n=new node(value);
			if(pos==1)
			{
				head=new node(value,head);
			}
			else
			{
				for(int i=1;i<(pos-1);i++)
				{
					tmp=tmp->next;
					n->next=tmp->next;
					tmp->next=n;
				}
			}
		}
		void insert_pos_after()
		{
			int value,pos;
			cout<<"Enter Position to insert=";
			cin>>pos;
			cout<<"Enter Value=";
			cin>>value;
			node *n=new node(value);
			node *tmp=head;
			for(int i=1;i<pos;i++)>
			{
				tmp=tmp->next;
				n->next=tmp->next;
				tmp->next=n;
			}
		}
		void del_first()
		{
			if(head==0)
			{
				cout<<"List is Empty"<<endl;
			}
			else
			{
				head=head->next;			
			}
			cout<<"First Node Deleted...!"<<endl;
		}
		void del_last()
		{
			if(head==0)
			{
				cout<<"List is Empty"<<endl;
			}
			else
			{
				node *tmp=head;
				while(tmp->next->next!=0)
				{
					tmp=tmp->next;
				}
				tmp->next=0;
				cout<<"Last Node Deleted...!"<<endl;
			}
		}
		void del_pos()
		{
			int p;
			if(head==0)
			{
				cout<<"List is Empty"<<endl;
			}
			else
			{
				node *tmp=head;
				cout<<"Insert Position=";
				cin>>p;
				for(int i=1;i<(p-1);i++)
				{
					tmp=tmp->next;
				}
				tmp->next=tmp->next->next;
			}
			cout<<"Node Deleted...!"<<endl;
		} 
		void display()
		{
			node *tmp=head;
			cout<<"Address of Head="<<head<<endl;
			cout<<endl;
			if(head==NULL)
			{
                    cout<<"List is Empty...!"<<endl;
            }
            else
            {
			    while(tmp->next!=head)
			    {
				 cout<<"Value:"<<tmp->data<<endl;
				 tmp=tmp->next;
			    }
		     cout<<"Value:"<<tmp->data<<"   "<<"Next Address="<<tmp->next<<endl;		
             }
        }
		void update()
		{
			int p;
			int value;
			if(head==0)
			{
				cout<<"List is Empty"<<endl;
			}
			else
			{
				node *tmp=head;
				cout<<"Insert Position of node=";
				cin>>p;
				cout<<"Insert new Value=";
				cin>>value; 
				for(int i=1;i<p;i++)>
				{
					tmp=tmp->next;
					if(i==p)
					{
						break;
					}
				}
				tmp->data=value;
				cout<<"Value Updated in the node...!"<<endl;
				
			}
		}
};
int main()
{
	//node n;
	link l;
	int ch;
	char i;
	do
	{
		cout<<"**************** LINKED LIST ****************"<<endl;
		cout<<"1: INSERT NODE"<<endl;
		cout<<"2: REMOVE NODE"<<endl;
		cout<<"3: UPDATE VALUE IN NODE"<<endl;
		cout<<"4: DISPLAY"<<endl;
		cout<<"5: EXIT"<<endl;
		cout<<endl;
		cout<<"Enter your choice=";
		cin>>ch;	
		switch(ch)
		{
			case 1:	cout<<"A: INSERT NODE FIRST"<<endl;
				cout<<"B: INSERT NODE LAST"<<endl;
				/*cout<<"C: INSERT NODE BEFORE"<<endl;
				cout<<"D: INSERT NODE AFTER"<<endl;*/
				cout<<"*****************************"<<endl;
				cout<<"Enter Choice=";
				cin>>i;
				switch(i)
				{
					case 'A': l.insert_first();
					          break;
						
					case 'B': l.insert_last();
						  break;
	
					/*case 'C': l.insert_pos_before();
						   break;

					case 'D': l.insert_pos_after();
						  break;*/
					
					default: cout<<"Invalid Option...!"<<endl;
						 break;
				}
				break;

			case 2: cout<<"A: DELETE NODE FIRST"<<endl;
				cout<<"B: DELETE NODE LAST"<<endl;
				cout<<"C: DELETE NODE FROM THE DESIRED POSITION"<<endl;
				cout<<"*****************************"<<endl;
				cout<<"Enter Choice=";
				cin>>i;
				switch(i)
				{
					case 'A': l.del_first();
					          break;
						
					case 'B': l.del_last();
						  break;
	
					case 'C': l.del_pos();
						   break;
					
					default: cout<<"Invalid Option...!"<<endl;
						 break;
				}
				break;

			case 3: l.update();
				break;

			case 4: l.display();
				break;
			
			default: cout<<"Invalid Choice.."<<endl;
				 break;			
		}
	}while(ch>0 && ch<5);

	return 0;
}