C语言双向循环链表

MT_125 2022-06-20 我要评论

实现细节

1、带一个哨兵位（哨兵节点，初始节点，不存储有效数据，用来方便后期数据的存储与查找）

2、与单向链表不同的是，双向链表中每个数据节点包含两个指针，分别指向前后两个节点

3、双向链表是循环的，其尾节点后不是空指针，而是与头部的哨兵节点通过指针相连

辅助理解图

具体实现代码

1、对链表进行初始化

初始化：哨兵位的前后指针均指向哨兵节点本身

void ListInit(ListNode** pphead)
{
    *pphead = (ListNode*)malloc(sizeof(ListNode));
    if (*pphead == NULL)
    {
        perror("ListInit");
        exit(-1);
    }
    (*pphead)->date = -1;
    (*pphead)->next = *pphead;
    (*pphead)->prev = *pphead;
}

2、任意位置前的插入

注意：插入位置前后节点中的前后指针要进行相应的更换

void Any_insert(ListNode* pos,Listtype date)
{
    ListNode* Prev = pos->prev;
//建立新节点
    ListNode* NewNode = (ListNode*)malloc(sizeof(ListNode));
    if (NewNode == NULL)
    {
        perror("Any_insert");
        exit(-1);
    }
    NewNode->date = date;
    NewNode->next = pos;
    pos->prev = NewNode;
    Prev->next = NewNode;
    NewNode->prev = Prev;
}

3、任意位置的删除

细节点：当链表中没有数据时，就不用删除，因此需要建立一个函数进行判断

bool Determine(ListNode* pphead)
{//判断链表中有无元素
    assert(pphead);
    return pphead == pphead->next; 
}
 
void Any_delet(ListNode* pos)
{
    assert(!Determine(pos));
    ListNode* Next = pos->next;
    ListNode* Prev = pos->prev;
    Next->prev = Prev;
    Prev->next = Next;
    free(pos);
}

4、头插和尾删

此处的插入和删除，十分方便，即：对上面的任插和任删进行套用

头插如下：

void Head_insert(ListNode* pphead, Listtype date)
{
    ListNode* NewNode = (ListNode*)malloc(sizeof(ListNode));
    if (NewNode == NULL)
    {
        perror("Head_insert");
        exit(-1);
    }
 
    //单独实现
    //NewNode->date = date;
    //NewNode->prev = pphead;
    //NewNode->next = pphead->next;
    //pphead->next->prev = NewNode;
    //pphead->next = NewNode;
    
    //进行任插的复用
    Any_insert(pphead->next ,date);
 
}

尾删如下：

void Tail_delet(ListNode* pphead)
{
    assert(pphead);
 
    //单独实现
    //assert(Determine(pphead));
    /*ListNode* tail = pphead->prev;
    if (tail != pphead)
    {
        ListNode* tailprev = tail->prev;
        tailprev->next = pphead;
        pphead->prev = tailprev;
        free(tail);
    }*/
 
    //尾删的复用
    Any_delet(pphead->prev);
}

完整代码

头文件

#pragma once
#include<stdio.h>
#include<malloc.h>
#include<stdlib.h>
#include<assert.h>
#include<stdbool.h>
 
typedef int Listtype;
 
typedef struct ListNode
{
	struct ListNode* prev;
    Listtype date;
	struct ListNode* next;
}ListNode;
 
void ListInit(ListNode** pphead);                      //链表初始化
void ListNode_ADD(ListNode* pphead, Listtype date);    //尾插
void Head_insert(ListNode* pphead, Listtype date);     //头插
void ListNode_Print(ListNode* pphead);                 //链表打印
void Tail_delet(ListNode* pphead);                     //尾删
bool Determine(ListNode* pphead);                      //判断表中有无数据
void Any_insert(ListNode* pos, Listtype date);         //任插
void Any_delet(ListNode* pos);                         //任删
void List_Destory(ListNode* pos);                      //链表清空

具体函数

#define _CRT_SECURE_NO_WARNINGS 1
#include "List.h" 
 
//链表打印
void ListNode_Print(ListNode* pphead)
{
	assert(pphead);
	ListNode* phead = pphead;
	pphead = pphead->next;
	for (; pphead != phead; pphead = pphead->next)
	{
		printf("%d ", pphead->date);
	}
	printf("\n");
}
 
bool Determine(ListNode* pphead)
{//判断链表中有无元素
	assert(pphead);
	return pphead == pphead->next; 
}
 
//链表初始化
void ListInit(ListNode** pphead)
{
	*pphead = (ListNode*)malloc(sizeof(ListNode));
	if (*pphead == NULL)
	{
		perror("ListInit");
		exit(-1);
	}
	(*pphead)->date = -1;
	(*pphead)->next = *pphead;
	(*pphead)->prev = *pphead;
}
 
//尾插
void ListNode_ADD(ListNode* pphead,Listtype date)
{
	//ListNode* NewNode = (ListNode*)malloc(sizeof(ListNode));
	//if (NewNode == NULL)
	//{
	//	perror("ADD_malloc");
	//	exit(-1);
	//}
	//NewNode->date = date;
	//NewNode->prev = pphead->prev;
	//pphead->prev->next = NewNode;
	//pphead->prev = NewNode;
	//NewNode->next = pphead;
 
	//任插的复用
	Any_insert(pphead, date);
 
}
void Head_insert(ListNode* pphead, Listtype date)
{
	ListNode* NewNode = (ListNode*)malloc(sizeof(ListNode));
	if (NewNode == NULL)
	{
		perror("Head_insert");
		exit(-1);
	}
	//NewNode->date = date;
	//NewNode->prev = pphead;
	//NewNode->next = pphead->next;
	//pphead->next->prev = NewNode;
	//pphead->next = NewNode;
    
	//进行任插的复用
	Any_insert(pphead->next ,date);
 
}
 
void Tail_delet(ListNode* pphead)
{
	assert(pphead);
	//assert(Determine(pphead));
	
	/*ListNode* tail = pphead->prev;
	if (tail != pphead)
	{
		ListNode* tailprev = tail->prev;
		tailprev->next = pphead;
		pphead->prev = tailprev;
		free(tail);
	}*/
 
	//尾删的复用
	Any_delet(pphead->prev);
}
 
//在任意位置前插入
void Any_insert(ListNode* pos,Listtype date)
{
	ListNode* Prev = pos->prev;
	ListNode* NewNode = (ListNode*)malloc(sizeof(ListNode));
	if (NewNode == NULL)
	{
		perror("Any_insert");
		exit(-1);
	}
	NewNode->date = date;
	NewNode->next = pos;
	pos->prev = NewNode;
	Prev->next = NewNode;
	NewNode->prev = Prev;
}
 
//任意位置删除
void Any_delet(ListNode* pos)
{
	assert(!Determine(pos));
	ListNode* Next = pos->next;
	ListNode* Prev = pos->prev;
	Next->prev = Prev;
	Prev->next = Next;
	free(pos);
}
 
//链表清空
void List_Destory(ListNode* pos)
{
	ListNode* head = pos,*Prev = pos->prev;
	for (pos = pos->prev; head != pos;pos = Prev)
	{
		Prev = pos->prev;
		Any_delet(pos);
	}
	printf("\n清空完成\n");
}

测试

#define _CRT_SECURE_NO_WARNINGS 1
#include "List.h"
 
void ListTest(ListNode** pphead)
{
	ListInit(pphead);
	Head_insert(*pphead, 60);
	Head_insert(*pphead, 100);
	Head_insert(*pphead, 60);
	Head_insert(*pphead, 50);
	ListNode_Print(*pphead);
 
	Tail_delet(*pphead);
	Tail_delet(*pphead);
	Tail_delet(*pphead);
 
	ListNode_Print(*pphead);
}
 
int main()
{
	ListNode* pphead = NULL;
	ListTest(&pphead);
 
	return 0 ;
}