slistnode.cs

用图像表示链表的创建、插入和删除

using System;
using System.Collections.Generic;
using System.Text;

namespace Example
{
    class SListnode
    {
        internal int data;
        internal SListnode next;

        public SListnode()
        {
            next = null;
        }

        public SListnode(int data)
        {
            this.data = data;
            next = null;
        }

        public SListnode(int data, SListnode next)
        {
            this.next = next;
            this.data = data;
        }

        public SListnode Nextnode()
        {
            return next;
        }

        public int Getdata()
        {
            return data;
        }

    }

    class SList
    {
        public SListnode head;
        public SListnode current;

        public SList()
        {
            head = null;
            current = null;
        }

        public void MakeEmpty()
        {
            head.next = null;
            current = head;
        }

        public int Length()
        {
            if (current != null)
            {
                SListnode a = head;
                int i = 0;
                while (a.next != null)
                {
                    a = a.next;
                    i++;
                }
                return i;
            }
            else
            {
                return -1;
            }
        }

        public void SetCurrent(SListnode cp)
        {
            current = cp;
        }

        public SListnode GetCurrent()
        {
            return current;
        }

        public SListnode Getnext()
        {
            return current.next;
        }

        public SListnode Gethead()
        {
            return head;
        }

        public SListnode getnode(int i)
        {
            if (i < 0)
                return null;
            if (i == 0)
                return head;
            SListnode p = head;
            for (int j = 1; p != null && j <= i; j++)
            {
                p = p.next;
            }
            return current;
        }

        //在单链表的当前结点的位置前插入一个值为item的结点 
        public void insert(int value,bool before)
        {
       
            if (current == head)
                before = false;  
            SListnode newnode;
            if (before)
            {
                SListnode p = head;
                while (p.next != current)
                    p = p.next;
                newnode = new SListnode(value, p.next);
                p.next = newnode;
            }
            else
            {
                newnode = new SListnode(value, current.next );
                current.next = newnode;
 
            }
        }

        public void insert(int value, int i)
        {
            if (i < 1)
                i = 1;
            if(i>Length()+1)
                i=Length()+1;
            SListnode p=getnode(i-1);
            SListnode newnode = new SListnode(value, p.next);
            p.next = newnode;
        }
        public void delete()
        {
            if (current == head)
                return;
            SListnode p = head;
            while (p.next != current)
                p = p.next;
            p.next = current.next;
            if (p.next != null)
                current = p.next;
            else
                current = p;
        }

        public void modifydata(int value)
        { current.data = value; }

    }
}