C中写一个双向链表，实现增删查改的功能

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本文链接： https://blog.csdn.net/ZhangaZhaoLong/article/details/85163909

1. #define _CRT_SECURE_NO_WARNIGS 1

   #include <stdio.h>
   #include <assert.h>
   
   typedef struct DListNode
   {
   	int data;
   	struct DListNode *next;
   	struct DListNode *prev;
   }DListNode;
   
   typedef struct DList
   {
   	DListNode *head;
   }DList;
   
   DListNode *BuyNode(int data)
   {
   	DListNode *node = (DListNode*)malloc(sizeof(DListNode));
   	assert(node != NULL);
   
   	node->data = data;
   	node->next = NULL;
   	node->prev = NULL;
   
   	return node;
   }
   
   void DListInit(DList *list)
   {
   	assert(list != NULL);
   	DListNode *head = BuyNode(0);
   	head->next = head;
   	head->prev = head;
   	list->head = head;
   }
   
   void DLNPushFront(DList *list, int data)   
   {
   	assert(list != NULL);
   	DListNode *node = BuyNode(data);
   	node->prev = list->head;
   	node->next = list->head->next;
   	list->head->next->prev = node;    //这句必须在前否则会造成传址失误
   	list->head->next = node;
   }
   
   void DLNPushBack(DList *list, int data)
   {
   	assert(list != NULL);
   	DListNode *node = BuyNode(data);
   	node->next = list->head;
   	node->prev = list->head->prev;
   	list->head->prev->next = node;      //这句必须在前否则会造成传址失误
   	list->head->prev = node;
   }
   
   void DLNPopFront(DList *list)
   {
   	assert(list != NULL);
   	assert(list->head->next != list->head);
   	DListNode *old = list->head->next;              //记得创建old不能直接freelist->head->next
   	list->head->next->next->prev = list->head;  //这里也要注意顺序
   	list->head->next = list->head->next->next;
   	free(old);
   }
   
   void DLNPopBack(DList *list)
   {
   	assert(list != NULL);
   	assert(list->head->next != list->head);
   	DListNode *old = list->head->prev;            //记得创建old不能直接freelist->head->next
   	list->head->prev->prev->next = list->head;
   	list->head->prev = list->head->prev->prev;//这里也要注意顺序
   	free(old);
   }
   
   void DLNInsert(DListNode *pos, int data)
   {
   	assert(pos != NULL);
   	DListNode *node = BuyNode(data);
   	node->next = pos;
   	node->prev = pos->prev;
   	pos->prev->next = node;
   	pos->prev = node;
   }
   
   void DLNPrint(DList *list)
   {
   	assert(list != NULL);
   	for (DListNode *cur = list->head->next; cur != list->head; cur = cur->next)
   	{
   		printf("%d--->", cur->data);
   	}
   	printf("\n");
   }
   
   void DLNErase(DListNode *pos)
   {
   	assert(pos != NULL);
   	pos->prev->next = pos->next;
   	pos->next->prev = pos->prev;
   	free(pos);
   }
   
   DListNode *DLNFind(DList *list, int data)
   {
   	assert(list != NULL);
   	DListNode *cur;
   	for (cur = list->head->next; cur != list->head; cur = cur->next)
   	{
   		if (cur->data == data)
   		{
   			return cur;
   		}
   	}
   	return NULL;
   }
   void DLNClear(DList *list)
   {
   	assert(list != NULL);
   	for (DListNode * cur = list->head->next; cur != list->head; cur = cur->next)
   	{
   		free(cur);
   	}
   	list->head->next = list->head;
   	list->head->prev = list->head;
   }
   
   void DLNDestory(DList *list)
   {
   	assert(list != NULL);
   	DLNClear(list);
   	free(list->head);
   	list->head = NULL;
   }
   int main()
   {
   	DList list;
   	DListNode pos;
   	DListInit(&list);
   	DLNPushFront(&list, 5);
   	DLNPushFront(&list, 6);
   	DLNPushFront(&list, 7);
   	DLNPrint(&list);
   	DLNPushBack(&list, 8);
   	DLNPushBack(&list, 9);
   	DLNPushBack(&list, 10);
   	DLNPrint(&list);
   	DLNPopFront(&list);
   	DLNPrint(&list);
   	DLNPopBack(&list);
   	DLNPrint(&list);
   	DLNInsert(DLNFind(&list, 5), 15);
   	DLNPrint(&list);
   	DLNErase(DLNFind(&list, 5));
   	DLNPrint(&list);
   
   	system("pause");
   	return 0;
   }