双向循环链表的建立到销毁

头文件：

#ifndef _LINKLIST_H
#define _LINKLIST_H

#define FAILURE    10000
#define SUCCESS    10001
#define TRUE       10002
#define FALSE      10003

typedef int ElemType; 

struct node     //双向循环链表
{
	ElemType data;   //数据域
	struct node *next;   //指针域   指向下一个
	struct node *prior;           //指向前一个
};

typedef struct node Node;

int LinkInit(Node **l);
int LinkInsert(Node *l, int n, ElemType e);
int LinkTraverse(Node *l, void (*p)(ElemType));
int LinkLength(Node *l);
int LinkEmpty(Node *l);
int GetElem(Node *l, int p, ElemType *e);
int LocateElem(Node *l, ElemType e, int (*p)(ElemType, ElemType));
int LinkDelete(Node *l, int p, ElemType *e);
int LinkClear(Node *l);
int LinkDestroy(Node **l);

#endif

子函数：

#include "LinkList.h"
#include <stdlib.h>
#include <stdio.h>

int LinkInit(Node **l)
{
	*l = (Node *)malloc(sizeof(Node) * 1);   //分配头结点   l 就是头指针
	if (NULL == *l)
	{
		return FAILURE;
	}

	(*l)->next = (*l);    //头结点指针域为l
	(*l)->prior = (*l);   //双向循环链表，头结点prior指针为l **

	return SUCCESS;
}

int LinkInsert(Node *l, int n, ElemType e)  //n 插入的位置
{
	Node *p = l;
	int k = 1;   //k 移动的次数

	if (NULL == l)    //入参判断
	{
		return FAILURE;
	}

	if (n > LinkLength(l) + 1)    //**
	{
		return FAILURE;
	}

	while (k < n)     //***
	{
		p = p->next;
		k++;
	}


	if (k > n)    //**
	{
		return FAILURE;
	}

	Node *q = (Node *)malloc(sizeof(Node) * 1);
	if (NULL == q)
	{
		return FAILURE;
	}


	q->data = e;
	q->prior = p;
	q->next = p->next;
	p->next = q;
	if (l != q->next)    //如果q不是最后一个结点 **
	{
		q->next->prior = q;
	}

	return SUCCESS;
}

int LinkTraverse(Node *l, void (*p)(ElemType))
{
	if (NULL == l)
	{
		return FAILURE;
	}
	Node *q = l;

	while (q->next != l)     //不等于本身  **
	{
		q = q->next;
		p(q->data);
	}

	return SUCCESS;
}

int LinkLength(Node *l)
{
	if (NULL == l)
	{
		return FAILURE;
	}

	int len = 0;
	Node *p = l->next;

	while (p != l)   //不等于本身 **
	{
		len++;
		p = p->next;
	}

	return len;
}

int LinkEmpty(Node *l)
{
	return (l->next == l && l->prior == l) ? TRUE : FALSE;  //**
}

int GetElem(Node *l, int p, ElemType *e)    //p 位置
{
	if (NULL == l || p < 1)   //入参判断  p不能小于0
	{
		return FAILURE;
	}

	Node *q = l->next;   //双向循环链表，q指向第一个结点  //**
	int i;

	for (i = 1; i < p && q != l; i++)    //循环p次，同时满足q不为空  双向循环链表 i = 1**
	{
		q = q->next;
	}

	if (q == l)      //如果q为空，说明p（位置）大于长度  **
	{
		return FAILURE;
	}

	*e = q->data;     //q已经指向第p个结点

	return SUCCESS;
}

int LocateElem(Node *l, ElemType e, int (*p)(ElemType, ElemType))
{
	if (NULL == l)
	{
		return FAILURE;
	}
	
	Node *q = l->next;
	int len = 1;

	while (q != l)     //双向循环链表  **
	{
		if (p(e, q->data) == TRUE)
		{
			return len;
		}
		q = q->next;
		len++;
	}

	return FAILURE;
}

int LinkDelete(Node *l, int p, ElemType *e)
{
	int k = 1;
	Node *q = l;

	if (l == NULL)
	{
		return FAILURE;
	}

	if (p > LinkLength(l) + 1)   //判断位置p是否合法  **
	{
		return FAILURE;
	}

	while (k < p)  //**
	{
		q = q->next;
		k++;
	}

	if (k > p)  //**
	{
		return FAILURE;
	}

	Node *n = q->next;
	*e = n->data;
	q->next = n->next;   
					     //如果不是最后一个  **

	n->next->prior = q;
	free(n);

	return SUCCESS;
}

int LinkClear(Node *l)
{
	if (NULL == l)
	{
		return FAILURE;
	}

	Node *p = l->next;

	while (p != l)  //**
	{
		l->next = p->next;
		//p->next->prior = l;
		free(p);
		p = l->next;
	}

	l->prior = l;   //**

	return SUCCESS;
}

int LinkDestroy(Node **l)
{
	if (l == NULL)
	{
		return FAILURE;
	}
	free(*l);
	(*l) = NULL;

	return SUCCESS;
}

主函数：

#include "LinkList.h"
#include <stdio.h>

void print(ElemType e)
{
	printf("%d ", e);
}

int equal(ElemType e1, ElemType e2)
{
	return (e1 == e2) ? TRUE : FALSE;
}
	

int main()
{
	int ret, i;
	Node *first = NULL;   //头指针

	srand(time(NULL));

	ret = LinkInit(&first);
	if (ret == FAILURE)
	{
		printf("Init Failure!\n");
	}
	else
	{
		printf("Init Success!\n");
	}

	for (i = 0; i < 10; i++)
	{
		ret = LinkInsert(first, i + 1, rand() % 20);
		if (ret == FAILURE)
		{
			printf("Insert Failure!\n");
		}
		else
		{
			printf("Insert Success!\n");
		}
	}

	ret = LinkTraverse(first, print);
	if (ret == FAILURE)
	{
		printf("\nTraverse Falure!\n");
	}
	else
	{
		printf("\nTraverse Success!\n");
	}


	ret = LinkLength(first);
	if (ret == FAILURE)
	{
		printf("Get Length Failure!\n");
	}
	else
	{
		printf("length %d\n", ret);
	}

	ret = LinkEmpty(first);
	if (ret == TRUE)
	{
		printf("List is empty!\n");
	}
	else if (ret == FALSE)
	{
		printf("List is not empty!\n");
	}

	int p = 10;
	ElemType e;
	ret = GetElem(first, p, &e);
	if (ret == FAILURE)
	{
		printf("Get element failure!\n");
	}
	else
	{
		printf("The %dth element is %d\n", p, e);
	}

	e = 10;
	ret = LocateElem(first, e, equal);
	if (FAILURE == ret)
	{
		printf("%d not exist!\n", e);
	}
	else
	{
		printf("%d is %dth element!\n", e, ret);
	}

	p = 1;
	ret = LinkDelete(first, p, &e);
	if (ret == FAILURE)
	{
		printf("Delete Failure!\n");
	}
	else
	{
		printf("Delete %d Success!\n", e);
	}

	ret = LinkTraverse(first, print);
	if (ret == FAILURE)
	{
		printf("\nTraverse Falure!\n");
	}
	else
	{
		printf("\nTraverse Success!\n");
	}

	ret = LinkClear(first);
	if (ret == SUCCESS)
	{
		printf("Clear Success!\n");
	}
	else
	{
		printf("Clear Failure!\n");
	}

	ret = LinkEmpty(first);
	if (ret == TRUE)
	{
		printf("List is empty!\n");
	}
	else if (ret == FALSE)
	{
		printf("List is not empty!\n");
	}

	ret = LinkDestroy(&first);
	if (ret == SUCCESS)
	{
		printf("Destroy Success!\n");
	}
	else
	{
		printf("Destroy Failure!\n");
	}

	for (i = 0; i < 10; i++)
	{
		ret = LinkInsert(first, i + 1, rand() % 20);
		if (ret == FAILURE)
		{
			printf("Insert Failure!\n");
		}
		else
		{
			printf("Insert Success!\n");
		}
	}

	return 0;
}