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<stdio.h>
#include<stdlib.h>
#include<assert.h>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