双向链表中间插入节点，删除节点

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

typedef int data_t;
typedef struct node
{
	data_t data;
	struct node* prev;
	struct node* next;
}node_t;
int dlist_create(node_t** head, data_t data);//函数声明创建链表
void dlist_showall(node_t* head);//函数声明遍历链表
int dlist_addhead(node_t** head, data_t data);//函数声明头插链表
int dlist_addtail(node_t** head, data_t data);//函数声明尾插链表
int dlist_insert(node_t** head, data_t,data_t );// 函数声明中间插链表
node_t* dlist_query(node_t** head, data_t data);//函数声明数据查询
int dlist_update(node_t** head, data_t old,data_t new_data);//函数声明链表更新
void dlist_destory(node_t* head);//函数声明销毁链表
int dlist_delete(node_t** head, data_t data);//函数声明删除节点

int dlist_create(node_t** head, data_t data)
{ 
	node_t* pnew = (node_t*)malloc(sizeof(node_t));
	if (pnew == NULL)
		return -1;

	pnew->data = data;
	pnew->prev = pnew->next = NULL;
	*head = pnew;
	return 0;
}
int dlist_addhead(node_t** head, data_t data)
{
	node_t* pnew = (node_t*)malloc(sizeof(node_t));
	if (pnew == NULL)
		return -1;

	pnew->data = data;
	pnew->prev = pnew->next = NULL;

	pnew->next = *head;
	if (*head)
	{
		(*head)->prev = pnew;
	}
	*head = pnew;
	
	return 0;
}
int dlist_addtail(node_t** head, data_t data)
{
	node_t* pnew = (node_t*)malloc(sizeof(node_t));
	if (pnew == NULL)
		return -1;

	pnew->data = data;
	pnew->prev = pnew->next = NULL;

	if (*head == NULL)//空链表，创建
	{
		*head = pnew;
		return 0;
	}

	node_t* p = *head;
	while (p->next)
	{ 
		p = p->next;
	}
	p->next = pnew;
	pnew->prev = p;
	return 0;

}

int dlist_insert(node_t** head, data_t pos, data_t new_data)
{
	// 创建新节点
	node_t* pnew = (node_t*)malloc(sizeof(node_t));
	if (pnew == NULL)
		return -1;
	pnew->data = new_data;

	// 空链表处理
	if (*head == NULL)
	{
		pnew->prev = NULL;
		pnew->next = NULL;
		*head = pnew;
		return 0;
	}

	node_t* p = *head;

	// 如果要插入的位置是头节点
	if (p->data == pos)
	{
		pnew->prev = NULL;
		pnew->next = p;
		p->prev = pnew;
		*head = pnew;
		return 0;
	}

	// 查找插入位置
	while (p != NULL)
	{
		if (p->data == pos)
		{
			// 在找到的节点前插入新节点
			pnew->next = p;
			pnew->prev = p->prev;
			p->prev->next = pnew;
			p->prev = pnew;
			return 0;
		}
		p = p->next;
	}

	// 如果没找到指定位置，则插入到尾部
	p = *head;
	while (p->next != NULL)
	{
		p = p->next;
	}
	p->next = pnew;
	pnew->prev = p;
	pnew->next = NULL;
	return 0;
}

node_t* dlist_query(node_t* head, data_t data)
{
	node_t* p = head;
	while (p)
	{
		if (p->data == data)  // 直接比较数据
			return p;         // 返回找到的节点指针
		p = p->next;
	}
	return NULL;
}


int dlist_update(node_t** head, data_t old, data_t new_data)
{
	node_t* p = dlist_query(*head, old);
	if (p == NULL)
		return 0;
	p->data = new_data;
	return 0;
}

int dlist_delete(node_t** head, data_t data)
{
	if (*head == NULL) return -1;  // 空链表检查

	node_t* p = *head;
	while (p)
	{
		if (p->data == data)
		{
			// 处理头节点情况
			if (p->prev == NULL)
			{
				*head = p->next;
				if (p->next)
					p->next->prev = NULL;
			}
			else
			{
				p->prev->next = p->next;
				if (p->next)  // 检查是否是尾节点
					p->next->prev = p->prev;
			}
			free(p);
			return 0;
		}
		p = p->next;
	}
	return -1;
}




void dlist_destory(node_t** head)
{
	node_t* p = *head;
	if (p == NULL)
		return;
	while (p->next)
	{
		p = p->next;
		free(p->prev);
	}
	free(p);
	*head = NULL;

}

void dlist_showall(node_t* head)
{
	node_t* p = head;
	while (p)
	{
		printf("%3d", p->data);
		p = p->next;
	}
	printf("\n");
}

int main()
{
	node_t* head = NULL;
	dlist_create(&head, 1024);
	for ( int i = 0; i < 6; i++)
		dlist_addtail(&head,i+1);
	dlist_showall(head);
	while (1)
	{
		printf("\n请输入要插入处节点数据（-1退出）：");
		data_t pos;
		scanf_s("%d", &pos);
		if (pos == -1)
			break;

		printf("请输入要插入的新数据：");
		data_t new_data;
		scanf_s("%d", &new_data);

		if (dlist_insert(&head, pos, new_data) == 0)
		{
			printf("插入后的链表内容：\n");
			dlist_showall(head);
		}
		else
		{
			printf("插入失败！\n");
		}
		
	}
	while (1)
	{
		printf("\n请输入要删除的节点数据（-1退出）：");
		data_t del_data;  // 正确声明变量
		scanf_s("%d", &del_data);

		if (del_data == -1)
			break;

		if (dlist_delete(&head, del_data) == 0)
		{
			printf("删除后的链表内容：\n");
			dlist_showall(head);
		}
		else
		{
			printf("删除失败！\n");  // 修正错误提示
		}
	}

	dlist_destory(&head);


	return 0;
}

运行结果

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