循环链表的C风格实现（单向）

头文件：

#ifndef _CIRCLELIST_H_
#define _CIRCLELIST_H_
typedef void CircleList;

//

typedef struct _tag_CircleListNode
{
	struct _tag_CircleListNode* next;
}CircleListNode;

//创建一个循环链表
CircleList* CircleList_Create();
//删除一个循环链表
void CircleList_Destroy(CircleList* list);
//清空一个循环链表
void CircleList_Clear(CircleList* list);
//返回链表的长度
int CircleList_Length(CircleList* list);
//在POS位置插入一个节点
int CircleList_Insert(CircleList* list, CircleListNode* node, int pos);
//获取POS位置节点的信息
CircleListNode* CircleList_Get(CircleList* list, int pos);
//删除POS位置的节点
CircleListNode* CircleList_Delete(CircleList* list, int pos);

////与游标相关的函数
//删除游标所指的位置节点
CircleListNode* CircleList_DeleteNode(CircleList* list, CircleListNode* node);
//重置游标位置
CircleListNode* CircleList_Reset(CircleList* list);
//当前游标位置
CircleListNode* CircleList_Current(CircleList* list);
//游标的NEXT域
CircleListNode* CircleList_Next(CircleList* list);

#endif

//Cpp

#include "circleList.h"
#include <iostream>

using namespace std;

//这个为头链表头
typedef struct _tag_CircleList
{
	CircleListNode header;
	CircleListNode* slider;
	int length;
}tagCircleList;

//创建一个循环链表
CircleList* CircleList_Create()
{
	tagCircleList* ret = (tagCircleList*)malloc(sizeof(tagCircleList));  //分配内存
	if (ret == NULL)
	{
		return NULL;
	}

	//初始化
	ret->header.next = NULL;
	ret->length = 0;
	ret->slider = NULL;

	return ret;
}

//删除一个循环链表
void CircleList_Destroy(CircleList* list)
{
	if (list = NULL)
	{
		return;
	}
	//释放内存
	free(list);
	return;
}

//清空一个循环链表
void CircleList_Clear(CircleList* list)
{
	tagCircleList* sList = NULL;
	sList = (tagCircleList*)list;
	if (sList == NULL)
	{
		return ;
	}
	//重置为初始化状态
	sList->header.next = NULL;
	sList->length = 0;
	sList->slider = NULL;
	return;
}

//返回链表的长度
int CircleList_Length(CircleList* list)
{
	tagCircleList* sList = NULL;
	sList = (tagCircleList*)list;
	int ret = -1;
	//异常处理
	if (list == NULL)
	{
		return ret;
	}
	
	return sList->length;
}

//在POS位置插入一个节点
int CircleList_Insert(CircleList* list, CircleListNode* node, int pos)
{
	tagCircleList* sList = NULL;
	sList = (tagCircleList*)list;
	int ret = -1;
	//异常处理
	if(list == NULL || node == NULL || pos<0)
	{
		return ret;
	}
	//临时变量Current
	CircleListNode* Current = (CircleListNode*)sList;

	for(int i = 0; (i < pos) && (Current->next != NULL); i++)
	{
		Current = Current->next;
	}

	node->next = Current->next;
	Current->next = node;

	//当长度为0时 游标指向node
	if (sList->length == 0)
	{
		sList->slider = node;
	}

	sList->length++;
	//如果current 依旧指向链表头 证明没跳走 是从0开始插入的 需要头插法
	if (Current == (CircleListNode*)sList)
	{
		//定义一个辅助last 变量来获取尾部节点的信息
		CircleListNode* last = (CircleListNode*)CircleList_Get(sList, sList->length - 1);
		//将尾部节点的NEXT域存为当前节点（头节点）
		last->next = Current->next;
	}
	return 0;
}

//获取POS位置节点的信息
CircleListNode* CircleList_Get(CircleList* list, int pos)
{

	tagCircleList* sList = (tagCircleList*)list;
	CircleListNode* ret = NULL;
	int i = 0;
	if (list == NULL || pos < 0)
	{
		return NULL;
	}
	CircleListNode* Current = (CircleListNode*)sList;
	for(i = 0; i < pos; i++)
	{
		Current = Current->next;
	}
	 
	ret = Current->next;
	return ret;
}

//删除POS位置的节点
CircleListNode* CircleList_Delete(CircleList* list, int pos)
{
	tagCircleList* sList = (tagCircleList*)list;
	CircleListNode* ret = NULL;

	if ((sList != NULL) && (pos >=0) && (sList->length > 0))
	{
		//将Current指向表头
		CircleListNode* Current = (CircleListNode*)(&(sList->header));
		//辅助节点last 进行头节点的删除使用 存取最后一个元素
		CircleListNode* last = NULL;

		for(int i = 0; i < pos; i++)
		{
			Current = Current->next;
		}
		//删除头结点
		if ( Current == (CircleListNode*)sList)
		{
			last = (CircleListNode*)CircleList_Get(sList, sList->length - 1);
		}
		//要删除的元素
		ret = Current->next;
		Current->next = ret->next;
		sList->length--;

		//判断链表非空
		if( last != NULL)
		{
			//sList->header.next = ret->next;
			Current->next = ret->next;
			last->next = ret->next;
		}
		//若删除的元素为游标所指的元素
		if(sList->slider = ret)
		{
			sList->slider = ret->next;
		}
		//若删除元素后 链表长度为0 做处理
		if (sList->length == 0)
		{
			sList->header.next = NULL;
			sList->slider = NULL;
		}
	}
	return ret;
}

////与游标相关的函数
//删除游标所指的位置节点
CircleListNode* CircleList_DeleteNode(CircleList* list, CircleListNode* node)
{
	tagCircleList* sList = (tagCircleList*)list;
	CircleListNode* ret = NULL;
	int i = 0;

	if (sList != NULL)
	{
		CircleListNode* Current = (CircleListNode*)sList;
		//循环查找node 在链表中的位置
		for (i = 0; i < sList->length; i++)
		{
			if (Current->next == node)
			{
				ret = Current->next;
				break;
			}

			Current = Current->next;
		}
		//找到了 使用CircleList_Delete 删除
		if(ret != NULL)
		{
			CircleList_Delete(list, i);
		}

	}

	return ret;
}

//重置游标位置
CircleListNode* CircleList_Reset(CircleList* list)
{
	tagCircleList* sList = (tagCircleList*)list;
	CircleListNode* ret = NULL;
	//如果不为空
	if (sList != NULL)
	{
		sList->slider = sList->header.next;
		ret = sList->slider;
	}

	return ret;
}

//当前游标位置
CircleListNode* CircleList_Current(CircleList* list)
{
	tagCircleList* sList = (tagCircleList*)list;
	CircleListNode* ret = NULL;
	//如果不为空
	if (sList != NULL)
	{
		ret = sList->slider;
	}

	return ret;
}

//把游标位置返回，游标下移
CircleListNode* CircleList_Next(CircleList* list)
{
	tagCircleList* sList = (tagCircleList*)list;
	CircleListNode* ret = NULL;
	//如果不为空
	if((sList != NULL) && (sList->slider != NULL))
	{
		ret = sList->slider;
		sList->slider = ret->next;
	}

	return ret;
}

测试框架如下：

#include "circleList.h"
#include <iostream>

using namespace std;

typedef struct _Temp_Test
{
	CircleListNode node;
	int temp;
	char temp2;
}TempTast;


int main()
{
	CircleList* circlelist = NULL;

	circlelist = CircleList_Create();
	//异常处理
	if (circlelist == NULL)
	{
		cout << "Create Err "  << endl;
		return -1;
	}

	TempTast t1, t2, t3, t4, t5;
	t1.temp = 1;
	t2.temp = 2;
	t3.temp = 3;
	t4.temp = 4;
	t5.temp = 5;
	//插入元素
	CircleList_Insert(circlelist, (CircleListNode*)(&t1), 0);
	CircleList_Insert(circlelist, (CircleListNode*)(&t2), 0);
	CircleList_Insert(circlelist, (CircleListNode*)(&t3), 0);
	CircleList_Insert(circlelist, (CircleListNode*)(&t4), 0);
	CircleList_Insert(circlelist, (CircleListNode*)(&t5), 0);
	//测试功能
	cout << "Length: " << CircleList_Length(circlelist) << endl;
	//遍历两次
	cout << "遍历两次:" << endl;
	for(int i = 0; i < 2*CircleList_Length(circlelist); i++)
	{
		cout <<"Node:" << ((TempTast*)CircleList_Get(circlelist, i))->temp << endl;
	}
	cout << endl;
	//删除第一个节点
	cout <<"Node:" << ((TempTast*)CircleList_Delete(circlelist, 0))->temp << endl;
	//清空
	CircleList_Clear(circlelist);
	cout << "After Clear Length: " << CircleList_Length(circlelist) << endl;

	//插入元素
	CircleList_Insert(circlelist, (CircleListNode*)(&t1), 0);
	CircleList_Insert(circlelist, (CircleListNode*)(&t2), 0);
	CircleList_Insert(circlelist, (CircleListNode*)(&t3), 0);
	CircleList_Insert(circlelist, (CircleListNode*)(&t4), 0);
	CircleList_Insert(circlelist, (CircleListNode*)(&t5), 0);
	//删除指定元素
	cout << "Delete Node :" << ((TempTast*)CircleList_DeleteNode(circlelist, (CircleListNode*)(&t1)))->temp << endl;
	//显示游标当前位置
	cout << "Silder Now :" << ((TempTast*)CircleList_Current(circlelist))->temp << endl;
	//移动后
	CircleList_Next(circlelist);
	cout << "Silder After Next :" << ((TempTast*)CircleList_Current(circlelist))->temp << endl;
	//重置后
	CircleList_Reset(circlelist);
	cout << "Silder After Reset :" << ((TempTast*)CircleList_Current(circlelist))->temp << endl;
	cout << endl;
	//销毁
	CircleList_Destroy(circlelist);
	cout << "circle has been Destroied" << endl;
	system("pause");
	return 0;
}