c语言实现带头双循环链表DCList的各种功能

本文链接：https://blog.youkuaiyun.com/S5242/article/details/113359704

双向循环链表与单向list相比较，虽然它的管理方式看起来比单向list复杂，多了一个前驱指针，但是它的实现就简单多了，因为它能轻松的找到当前节点的前驱节点进行操作。

1.DCList.h

链表增删改查等操作的实现；

#ifndef __DCLIST_H__
#define __DCLIST_H__

#include<string.h>
#include<assert.h>
#include<stdlib.h>
#include<stdio.h>
#include<windows.h>
#pragma warning(disable:4996)

#define ElemTepe  int

typedef struct DCListNode //链表节点
{
	ElemTepe  data;
	struct DCListNode* next;   //后继节点
	struct DCListNode* pre;  //前驱节点
}DCListNode;

typedef struct DCList //头节点  方便对节点的管理
{
	DCListNode* first;
	DCListNode* last;
	size_t size;
}DCList;




DCListNode* _BuyDCLNode(ElemTepe x) {   //申请一个链表节点
	DCListNode* s = (DCListNode*)malloc(sizeof(DCListNode));
	assert(s != NULL);
	s->next = s->pre = NULL;
	s->data = x;
	return s;
}

void DCSListInit(DCList* plist);  //初始化
void DCListShow(DCList* plist);   //自己添加了一个显示功能，方便查看
void DCListPushBack(DCList* plist, ElemTepe x);   //尾部插入
void DCListPushFront(DCList * plist, ElemTepe x);//头部插入
void DCListPopBack(DCList * plist);  //尾部删除
void DCListPopFront(DCList* plist);  //头部删除
void DCListClear(DCList* plist);    //清空
void DCListDestroy(DCList* plist);   //摧毁
void DCListReverse(DCList* plist);    //翻转
void DCListDeleteByVal(DCList* plist, ElemTepe x);   //按元素删除
DCListNode*  DCListFind(DCList* plist, ElemTepe x);   //按元素查找
void DCListInsertByVal(DCList* plist, ElemTepe x);      //按元素插入

void DCListReverse(DCList* plist) {
	assert(plist);
	DCListNode* p = plist->first->next;
	DCListNode* q ;
	if (plist->size <= 1) {
		return;
	}
	//将第一个节点与后面的节点断开
	q = p->next;
	p->next = plist->first;
	plist->first->pre = p;
	plist->last = p;
	
	while (q != plist->first) {//逐个去除后面的节点进行push_front
		p = q;
		q = q->next;
		p->next = plist->first->next;
		plist->first->next = p;
		p->pre = plist->first;
		p->next->pre = p;		
	}
}

void DCListPopBack(DCList* plist) {
	assert(plist);
	if (plist->first == plist->last) {
		printf("数据为空无法删除!\n");
	}
	DCListNode* p = plist->last;
	plist->last = p->pre;
	p->pre->next = p->next;
	p->next->pre = p->pre;
	free(p);
	plist->size--;
}

void DCListPopFront(DCList* plist)
{
	assert(plist);
	if (plist->first == plist->last) {
		printf("数据为空无法删除!\n");
	}
	DCListNode* p = plist->first->next;

	plist->first->next = p->next;
	p->next->pre = plist->first;
	if (p == plist->last) {//只有一个节点
		plist->last = plist->first;
	}
	free(p);
	plist->size--;
}

void DCListClear(DCList* plist) {
	assert(plist);
	DCListNode* p = plist->first->next;
	DCListNode* pre;
	while (p == plist->first) {
		pre = p;
		p = p->next;	
		free(pre);
	}
	plist->last = plist->first;
	plist->first->pre = plist->first->next = plist->first;
	plist->size = 0;
}

void DCListDestroy(DCList* plist) {
	DCListClear(plist);
	free(plist->first);
}


void DCSListInit(DCList* plist) {
	assert(plist);
	DCListNode* p = _BuyDCLNode(0);
	plist->first = plist->last = p;
	plist->first->next = plist->first->pre = p;
	plist->size = 0;
}

void DCListShow(DCList* plist) {
	DCListNode* p = plist->first->next;	
	while (p != plist->first) {
		printf("%d->", p->data);
		p = p->next;
	}
	printf("over \n");
}

void DCListPushBack(DCList* plist, ElemTepe x) {
	assert(plist);
	DCListNode* s = _BuyDCLNode(x);
	DCListNode* p = plist->last;
	s->pre = p;
	p->next = s;
	plist->last = s;
	s->next = plist->first;
	plist->first->pre = plist->last;
	plist->size++;
}

void DCListPushFront(DCList* plist, ElemTepe x) {
	assert(plist);
	DCListNode* s = _BuyDCLNode(x);
	DCListNode* p = plist->first;
	s->next = p->next;
	s->pre = p;
	s->pre->next = s;
	s->next->pre = s;
	plist->size++;
	if (plist->first == plist->last) {
		plist->last = s;
	}
}

DCListNode* DCListFind(DCList* plist, ElemTepe key) {
	assert(plist);
	DCListNode* p = plist->first->next;
	while ((plist->first != p)  &&  p->data != key) {
		p = p->next;
	}
	if (p == plist->first) {
		return NULL;
	}
	return p;
}

void DCListDeleteByVal(DCList* plist, ElemTepe key)
{
	assert(plist);
	DCListNode* s = DCListFind(plist, key);
	if (s == NULL) {
		printf("要删的值不存在");
		return;
	}
	if (s == plist->last) {
		plist->last = s->pre;
	}
	s->pre->next = s->next;
	s->next->pre = s->pre;
	free(s);
	plist->size--;
}

void DCListInsertByVal(DCList* plist, ElemTepe key) {
	assert(plist);
	DCListNode* s = _BuyDCLNode(key);
	DCListNode* p = plist->first->next;
	while ((plist->first != p) && p->data < key) {
		p = p->next;
	}

	p->pre->next = s;
	s->pre = p->pre;
	s->next = p;
	p->pre = s;
	if (p == plist->first) { //尾插
		plist->last = plist->first->pre;
	}
	plist->size++;
}

2.main.c

测试各个函数功能


#include"DCList.h"
int main()
{
	DCList mylist;
	DCSListInit(&mylist);
	ElemTepe item, key;
	int pos;
	DCListNode* p;
	int select = 1;
	while (select)
	{
		printf("********************************************\n");
		printf("* [0] quit_system      [1] push_back       *\n");
		printf("* [2] push_front       [3] show_list       *\n");
		printf("* [4] pop_back         [5] pop_front       *\n");
		printf("* [6] length           [7] insert_val      *\n");
		printf("* [8] delete_val       [9] find            *\n");
		printf("* [10] sort            [11] reverse        *\n");
		printf("* [12] remove_all      [13] clear          *\n");
		printf("********************************************\n");
		printf("请选择:>");
		scanf("%d", &select);
		switch (select)
		{
		case 1:
			printf("请输入要插入的数据(以-1结束):>");
			while (scanf("%d", &item), item != -1)  //逗号表达式
				DCListPushBack(&mylist, item);
			break;
		case 2:
			printf("请输入要插入的数据(以-1结束):>");
			while (scanf("%d", &item), item != -1)  //逗号表达式
				DCListPushFront(&mylist, item);
			break;
		case 3:
			DCListShow(&mylist);
			break;
		case 4:
			DCListPopBack(&mylist);
			break;
		case 5:
			DCListPopFront(&mylist);
			break;
		case 6:
			printf("表长为:>%d\n", mylist.size);
			break;		
		case 7:
			printf("请输入要插入的值:>");
			scanf("%d", &item);
			DCListInsertByVal(&mylist, item);
			break;
		case 8:
			printf("请输入要删除的值:>");
			scanf("%d", &key);
			DCListDeleteByVal(&mylist, key);
			break;		
		case 9:
			printf("请输入要查找的值:>");
			scanf("%d", &key);
			p = DCListFind(&mylist, key);
			if (p == NULL)
				printf("要查找的值%d不存在.\n", key);
			else
				printf("要查找的值%d存在.\n", key);
			break;
		case 10:
			DCListSort(&mylist);
			break;
		case 11:
			DCListReverse(&mylist);
			break;
		//case 12:
		//	printf("请输入要删除的值:>");
		//	scanf("%d", &key);
		//	DCSListRemoveAll(&mylist, key);
		//	break;
		case 13:
			DCListClear(&mylist);
			break;
		default:
			break;
		}
		system("pause");
		DCListShow(&mylist);
		/*system("cls");*/
	}
	DCListDestroy(&mylist);
	return 0;
}