带头结点循环链表

上一个说的是单链表，其实循环链表跟单链表类似，单链表最后一个节点(p)的next域为NULL即p->next=NULL而循环链表(plist)的则为头结点的地址，即p->next=plist。其余的基本操作和单链表几乎一样，仅仅是单链表循环结束条件为!=NULL，而循环链表是!=plist。

基本操作为：初始化，插入（头插、尾插），查找，删除，判空，求长，摧毁，逆置。

.cpp:

#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include "clist.h"


void InitList(CList plist)
{
	assert(plist != NULL);
	if(plist == NULL)
	{
		return ;
	}

	plist->next = plist;//循环链表
}

//头插
bool Insert_Head(CList plist,int val)
{
	CNode *p = (CNode *)malloc(sizeof(CNode));
	assert(p != NULL);//

	p->data = val;

	p->next = plist->next;//
	plist->next = p;

	return true;
}

//尾插
bool Insert_Tail(CList plist,int val)
{
	CNode *p;
	for(p=plist;p->next!=plist;p=p->next)
	{
		;
	}
	CNode *q = (CNode *)malloc(sizeof(CNode));
	q->data = val;

	//q插在p的后面
	q->next = p->next;//q->next = plist;
	p->next = q;

	return true;
}


CNode *Search(CList plist,int key)//List 
{
	for(CNode *p=plist->next;p!=plist;p=p->next)
	{
		if(p->data == key)
		{
			return p;
		}
	}

	return NULL;
}

bool Delete(CList plist,int key)
{
	CNode *p = Search(plist,key);
	CNode *q;
	if(p == NULL)
	{
		return false;
	}
	if(p->next != plist)//p不是最后的节点,删除p后面的点，将后面的数据赋值到p中
	{
		q = p->next;
		p->next = q->next;
		p->data = q->data;
		free(q);
	}
	else//p是最后一个点
	{
		for(q=plist;q->next!=p;q=q->next) ;//找到p的前驱，然后删除p

		q->next = p->next;
		free(p);
	}

	return true;
}

bool IsEmpty(CList plist)
{
	return plist->next == plist;
}

int GetLength(CList plist)
{
	int count = 0;
	for(CNode *p=plist->next;p!=plist;p=p->next)
	{
		count++;
	}

	return count;
}

void Show(CList plist)
{
	for(CNode *p=plist->next;p!=plist;p=p->next)
	{
		printf("%d ",p->data);
	}
	printf("\n");
}

void Clear(CList plist)
{
	Destroy(plist);
}

void Destroy(CList plist)
{
	CNode *p;
	while(plist->next != plist)
	{
		p = plist->next;
		plist->next = p->next;
		free(p);
	}
}

void Revers(CList plist)
{
	if(plist==NULL||plist->next==NULL||plist->next->next==NULL)
	{
		return;
	}
	CNode *p=plist->next;
	CNode *q;
	plist->next=plist;
	while(p!=plist)
	{
		q=p->next;
		p->next=plist->next;
		plist->next=p;
		p=q;
	}
}

.h:

#pragma once
//循环链表,尾节点的next指向头节点

typedef struct CNode
{
	int data;
	struct CNode *next;
}CNode,*CList;

void InitList(CList plist);//Node *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);//List 

bool Delete(CList plist,int key);

bool IsEmpty(CList plist);

int GetLength(CList plist);

void Show(CList plist);

void Clear(CList plist);

void Destroy(CList plist);

void Revers(CList plist);