C++双向链表的增删查改操作方法讲解

typedef int LTDataType;
typedef struct ListNode
{
	LTDataType _data;
	struct ListNode* _next;
	struct ListNode* _prev;
}ListNode;

ListNode* ListCreate()
{
	ListNode* guard = (ListNode*)malloc(sizeof(ListNode));
	if (guard == NULL)
	{
		perror("ListCreate");
		exit(-1);
	}
	guard->_next = guard;
	guard->_prev = guard;
	return guard;
}

void ListPrint(ListNode* pHead)
{
	assert(pHead);
	ListNode* cur = pHead;
	while (cur->_next != pHead)
	{
		cur = cur->_next;
		printf("%d->", cur->_data);
	}
	printf("NULL\n");
	return;
}

void ListPushBack(ListNode* pHead, LTDataType x)
{
	ListNode* newnode = (ListNode*)malloc(sizeof(ListNode));
	if (newnode == NULL)
	{
		perror("ListPushBack");
		exit(-1);
	}
	newnode->_data = x;
	ListNode* cur = pHead->_prev;
	newnode->_next = pHead;
	newnode->_prev = cur;
	cur->_next = newnode;
	pHead->_prev = newnode;
	return;
}

void ListPopBack(ListNode* pHead)
{
	assert(pHead);
	ListNode* pre = pHead->_prev->_prev;
	free(pHead->_prev);
	pre->_next = pHead;
	pHead->_prev = pre;
	return;
}

void ListPushFront(ListNode* pHead, LTDataType x)
{
	assert(pHead);
	ListNode* newnode = (ListNode*)malloc(sizeof(ListNode));
	if (newnode == NULL)
	{
		perror("ListPushFront");
		exit(-1);
	}
	newnode->_data = x;
	newnode->_next = pHead->_next;
	newnode->_prev = pHead;
	pHead->_next = newnode;
	newnode->_next->_prev = newnode;
	return;
}

void ListPopFront(ListNode* pHead)
{
	assert(pHead);
	ListNode* cur = pHead->_next->_next;
	free(pHead->_next);
	pHead->_next = cur;
	cur->_prev = pHead;
	return;
}

ListNode* ListFind(ListNode* pHead, LTDataType x)
{
	assert(pHead);
	ListNode* cur = pHead;
	while (cur->_next != pHead)
	{
		cur = cur->_next;
		if (cur->_data == x)
			return cur;
	}
	printf("Can't find.\n");
	return NULL;
}

void ListInsert(ListNode* pos, LTDataType x)
{
	assert(pos);
	ListNode* newnode = (ListNode*)malloc(sizeof(ListNode));
	if (newnode == NULL)
	{
		perror("ListPushFront");
		exit(-1);
	}
	ListNode* cur = pos->_prev;
	newnode->_next = pos;
	newnode->_prev = cur;
	pos->_prev = newnode;
	cur->_next = newnode;
	return;
}

void ListErase(ListNode* pos)
{
	ListNode* front = pos->_prev;
	ListNode* behind = pos->_next;
	free(pos);
	front->_next = behind;
	behind->_prev = front;
	return;
}

void ListDestory(ListNode* pHead)
{
	assert(pHead);
	while (pHead->_next != pHead)
	{
		pHead->_next = pHead->_next->_next;
		free(pHead->_next->_prev);
		pHead->_next->_prev = pHead;
	}
	return;
}