顺序结构双链表的实现

双链表是用最快的时间实现链表的一种方式，具体的实现代码如下：

#pragma once
#include
#include
#include

typedef int LTDataType;
typedef struct ListNode
{
	LTDataType data;
	struct ListNode* next;//下一个节点
	struct ListNode* prev;//上一个节点
}LTNode;

//初始化
LTNode* LTInit();
//销毁
void LTDestroy(LTNode* phead);
//打印
void LTPrint(LTNode* phead);
//bool LTEmpty(LTNode* phead);
//尾插
void LTPushBack(LTNode* phead, LTDataType x);
//尾删
void LTPopBack(LTNode* phead);
//头插
void LTPushFront(LTNode* phead, LTDataType x);
//头删
void LTPopFront(LTNode* phead);

#include"dlist.h"
//创建新节点
LTNode* CreateLTNode(LTDataType x)
{
	LTNode* newnode = (LTNode*)malloc(sizeof(LTNode));
	if (newnode == NULL)
	{
		perror("malloc fail");
		exit(-1);
	}
	newnode->data = x;
	newnode->next = NULL;
	newnode->prev = NULL;
	return newnode;
}
//初始化
LTNode* LTInit()
{
	LTNode* phead = CreateLTNode(-1);
	phead->next = phead;
	phead->prev = phead;
	return phead;
}
//销毁
void LTDestroy(LTNode* phead)
{
	assert(phead);
	LTNode* cur = phead->next;
	while (cur != phead)
	{
		LTNode* next = cur->next;
		free(cur);
		cur = next;
	}
	free(phead);
	phead = NULL;
}
//打印
void LTPrint(LTNode* phead)
{
	assert(phead);
	LTNode* cur = phead->next;
	while (cur != phead)
	{
		printf("%d<=>", cur->data);
		cur = cur->next;
	}
	printf("NULL\n");
}
//尾插
void LTPushBack(LTNode* phead, LTDataType x)
{
	LTNode* newnode = CreateLTNode(x);
	LTNode* tail = phead->prev;
	newnode->prev = tail;
	newnode->next = phead;

	tail->next = newnode;
	phead->prev = newnode;
}
//尾删
void LTPopBack(LTNode* phead)
{
	assert(phead);
	LTNode* tail = phead->prev;
	tail->prev->next = phead;
	phead->prev = tail->prev;
	free(tail);
	tail = NULL;
}
//头插
void LTPushFront(LTNode* phead, LTDataType x)
{
	assert(phead);
	LTNode* newnode = CreateLTNode(x);
	LTNode* next = phead->next;
	phead->next = newnode;
	newnode->prev = phead;
	newnode->next = next;
	next->prev = newnode;
}
//头删
void LTPopFront(LTNode* phead)
{
	assert(phead);
	LTNode* cur = phead->next;
	phead->next = cur->next;
	cur->next->prev = phead;
	free(cur);
	cur = NULL;
}

在初始化的过程中，因为要改变phead的值，所以要传入二级指针 ，但是为了保证统一，只需要初始化的时候返回一个节点指针就可以避免传入二级指针