C语言实现链表常用接口(双向带头循环链表)

• 定义节点
• 初始化链表
• 创建节点
• 尾插
• 头插
• 尾删
• 头删
• 查找节点
• 后插
• 前插
• 删除任意位置节点
• 打印链表所有节点
• 销毁链表

typedef int dataType;
typedef struct ListNode ListNode;
struct ListNode
{
	ListNode* prev;
	dataType data;
	ListNode* next;
};

void initList(ListNode* head)
{
	head->next = head;
	head->prev = head;
}

ListNode* createNode(dataType x)
{
	ListNode* node = malloc(sizeof (ListNode));
	node->data = x;
	return node;
}

void listPushBack(ListNode* head, dataType x)
{
	assert(head != NULL);
	ListNode* tail = head->prev;
	ListNode* node = createNode(x);
	tail->next = node;
	node->prev = tail;
	node->next = head;
	head->prev = node;	
}

void listPushFront(ListNode* head, dataType x)
{
	assert(head != NULL);
	ListNode* first = head->next;
	ListNode* node = createNode(x);
	head->next = node;
	node->prev = head;
	node->next = first;
	first->prev = node;
}

void listPopBack(ListNode* head)
{
	assert(head->next != NULL);
	ListNode* tail = head->prev;
	ListNode* tailPrev = tail->prev;
	tailPrev->next = head;
	head->prev = tailPrev;
	free(tail);
}

void listPopFront(ListNode* head)
{
	assert(head->next != NULL);
	ListNode* first = head->next;
	ListNode* second = first->next;
	head->next = second;
	second->prev = head;
	free(first);
}

ListNode* findNode(ListNode* head, dataType x)
{
	ListNode* cur = head->next;
	while (cur != head)
	{
		if (cur->data == x)
			return cur;
		cur = cur->next;
	}
	return NULL;
}

void listInsertAfter(ListNode* pos, dataType x)
{
	assert(pos != NULL);
	ListNode* next = pos->next;
	ListNode* node = createNode(x);
	pos->next = node;
	node->prev = pos;
	node->next = next;
	next->prev = node;
}

void listInsertBefore(ListNode* pos, dataType x)
{
	assert(pos != NULL);
	ListNode* prev = pos->prev;
	ListNode* node = createNode(x);
	prev->next = node;
	node->prev = prev;
	node->next = pos;
	pos->prev = node;
}

void listErase(ListNode* pos)
{
	assert(pos != NULL);
	assert(pos != head);
	ListNode* prev = pos->prev;
	ListNode* next = pos->next;
	prev->next = next;
	next->prev = prev;
	free(pos);
}

void printList(ListNode* head)
{
	ListNode* cur = head->next;
	while (cur != head)
	{
		printf("%d->", cur->data);
		cur = cur->next;
	}
	printf("NULLn");
}

void destroyList(ListNode* head)
{
	ListNode* cur = head->next;
	while (cur != head)
	{
		ListNode* next = cur->next;
		free(cur);
		cur = next;
	}
	free(head);
}