循环链表的操作详解

一、概述

循环链表：循环链表是另一种形式的链式存贮结构。它的特点是表中最后一个结点的指针域指向头结点，整个链表形成一个环。

从上图看出循环链表有两个成员：data 和 next

由此可创建循环链表和它的一些基本操作如下：

注明：它的操作其实与单链的操作差不多，只要注意判断标志即可。

#pragma once//循环链表,尾节点的next指向头typedef struct CNode  //宏定义{int data;struct CNode *next;}CNode,*CList;//CList==CNode*void InitList(CList plist);//头插bool Insert_head(CList plist,int val);//尾插bool Insert_tail(CList plist,int val);CNode *Search(CList plist,int key);bool Delete(CList plist,int key);bool IsEmpty(CList plist);int GetLength(CList plist);void Show(CList plist);void Destroy(CList plist);void Clear(CList plist);

链表操作实现：

void InitList(CList plist){assert(plist != NULL);plist->next = plist;}//头插bool Insert_head(CList plist,int val){CNode *p = (CNode *)malloc(sizeof(CNode));//创建新节点p->data = val;p->next = plist->next;//连线，防止数据丢失plist->next = p;return true;}//尾插bool Insert_tail(CList plist,int val){CNode *p = (CNode *)malloc(sizeof(CNode));p->data = val;CNode *q;for(q=plist;q->next!=plist;q=q->next) ;//->next==NULL//将p插入在q后面p->next = q->next;q->next = p;return true;}CNode *Search(CList plist,int key){CNode *p;for( p = plist;plist->next != plist;p=p->next)//遍历找key,注意链表的有效数据节点既是它的头，也是尾。{if(p->data == key) {return p;}}return NULL; }bool Delete(CList plist,int key){CNode *p;for(p=plist;p->next!=plist;p=p->next){if(p->next->data == key)//找到key的上一个节点位置{break;}}if(p->next == plist)//没有key{return false;}//将节点从链表中删除    CNode *q = p->next;p->next = q->next;//p->next = p->next->next;free(q);//释放内存return true;}bool IsEmpty(CList plist){return plist->next == NULL;}int GetLength(CList plist){int count = 0;//计数器for(CNode *p = plist;p->next != plist;p=p->next){count++;}return count;}void Destroy(CList plist){CNode *p;while(plist->next != plist){p = plist->next;plist->next = p->next;free(p);}}void Clear(CList plist){Destroy( plist);}void Show(CList plist){CNode *q;for(q=plist->next; q->next !=plist;q=q->next) {printf("%d ",q->data);}}

程序测试：

#include<stdio.h>#include<stdlib.h>#include<vld.h>#include"clist.h"//循环链表已完成int main(){CNode sa;InitList(&sa);int i;for(i=0;i<10;i++){Insert_tail(&sa,i);}//printf("%d ",Search(&sa,100));Delete(&sa,2);Delete(&sa,3);Delete(&sa,12);printf("%d\n",GetLength(&sa));//Destroy(&sa);//Destroy(&sa);//Destroy(&sa);Show(&sa);   return 0;}

运行结果：