using System;
using System.IO;
// 构成链表的结点定义 
public class Node 
{
 public Object data;
 public Node next;
 public Node( Object d ) 
 {
 data = d;
 next = null;
 }
}
public class List 
{
 // 用变量来实现表头
 private Node Head = null;
 private Node Tail = null;
 private Node Pointer = null;
 private int Length = 0;
 //清空整个链表 
 public void deleteAll( ) 
 {
 Head = null;
 Tail = null;
 Pointer = null;
 Length = 0;
 }
 //链表复位，使第一个结点 成为当前结点
 public void reset( ) 
 {
 Pointer = null;
 }
 //判断链表是否为空
 public bool isEmpty( ) 
 {
 return (Length == 0);
 }
 //判断当前结点是否 为最后一个结点
 public bool isEnd( ) 
 {
 if (Length == 0)
  throw new System.Exception( );
 else if (Length == 1)
  return true;
 else
  return (cursor( ) == Tail);
 }
 //返回当前结点的下一个结点的值， 并使其成为当前结点
 public Object nextNode( ) 
 {
 if (Length == 1)
  throw new System.Exception( );
 else if (Length == 0)
  throw new System.Exception( );
 else 
 {
  Node temp = cursor();
  Pointer = temp;
  if (temp != Tail)
  return (temp.next.data);
  else
  throw new System.Exception( );
 }
 }
 //返回当前结点的值
 public Object currentNode( ) 
 {
 Node temp = cursor( );
 return temp.data;
 }
 //在当前结点前插入一个结点， 并使其成为当前结点
 public void insert( Object d ) 
 {
 Node e = new Node( d );
 if (Length == 0) 
 {
  Tail = e;
  Head = e;
 } 
 else 
 {
  Node temp = cursor( );
  e.next = temp;
  if (Pointer == null)
  Head = e;
  else
  Pointer.next = e;
 }
 Length++;
 }
 //返回链表的大小
 public int size( ) 
 {
 return Length;
 }
 //将当前结点移出链表，下一个结点成为当前结点
 //如果移出的结点是最后一个结点，则第一个结点成为当前结点
 public Object remove( ) 
 {
 Object temp;
 if (Length == 0)
  throw new System.Exception( );
 else if (Length == 1) 
 {
  temp = Head.data;
  deleteAll( );
 } 
 else 
 {
  Node cur = cursor( );
  temp = cur.data;
  if (cur == Head)
  Head = cur.next;
  else if (cur == Tail) 
  {
  Pointer.next = null;
  Tail = Pointer;
  reset( );
  } 
  else
  Pointer.next = cur.next;
  Length--;
 }
 return temp;
 }
 //返回当前结点的指针
 private Node cursor( ) 
 {
 if (Head == null)
  throw new System.Exception( );
 else if (Pointer == null)
  return Head;
 else
  return Pointer.next;
 }
 //链表的简单应用举例
 public static void Main( ) 
 {
 List a = new List();
 for (int i = 1; i <= 10; i++)
  a.insert( new IntPtr(i));
 Console.WriteLine(a.currentNode( ));
 while (!a.isEnd( ))
  Console.WriteLine(a.nextNode( ));
 a.reset();
 while (!a.isEnd( )) 
 {
  a.remove( );
 }
 a.remove( );
 a.reset( );
 if (a.isEmpty( ))
  Console.WriteLine(\"There is no Node in List!\");
 Console.WriteLine(\"You can press return to quit!\");
 try 
 {
  // 确保用户看清程序运行结果
  Console.Read( );
 } 
 catch (IOException e) 
 {
 }
 }
}