C++实现双向链表

节点定义

template 
class Node
{
public:
	T val;
	class Node* next;
	class Node* prev;
	Node(T val) :val(val), next(NULL), prev(NULL) { ; }
	Node() : next(NULL), prev(NULL) { ; }
};

链表类实现

template 
class DList
{
private:
	Node* head;
	int num;
public:
	DList::DList()
	{
		head = new Node();
		head->next = head;
		head->prev = head;
		num = 1;
	}
	// 链表打印
	 
	void ListPrint()
	{
		Node* cur = head->next;
		while (cur != head)
		{
			cout << cur->val << " ";
			cur = cur->next;
		}
		cout << endl;
	}
	// 尾插
	 
	void ListPushBack(T val)
	{
		Node* newnode = new Node(val);

		newnode->prev = head->prev;
		head->prev->next = newnode;

		head->prev = newnode;
		newnode->next = head;
		num++;
	}
	// 尾删
	 
	void ListPopBack()
	{
		if (head->next == head)
			return;
		Node* tail = head->prev;
		head->prev = tail->prev;
		tail->prev->next = head;
		delete tail;
		num--;
		ListPrint();
	}
	// 头插
 
	void ListPushFront(T val)
	{
		Node* newnode = new Node(val);
		Node* nextnode = head->next;

		newnode->next = nextnode;
		nextnode->prev = newnode;
		head->next = newnode;
		newnode->prev = head;


		num++;
	}
	//头删
	 
	void ListPopFront()
	{
		// 判空
		if (head->next == head)
			return;

		Node* cur = head->next;
		Node* back = cur->next;
		back->prev = head;
		head->next = back;
		num--;
		delete cur;
	}

	// 查找链表中值为 val的的节点并返回
 
	Node* ListFind(T val)
	{
		Node* cur = head->next;
		while (cur != head)
		{
			if (cur->val == val)
				return cur;
			cur = cur->next;
		}
		return NULL;
	}
	// 节点插入
	 
	void ListInsert(int pos, T val)
	{
		assert(pos <= num && pos > 0);
		Node* newnode = new Node(val);
		Node* cur = head;
		while (--pos)
		{
			cur = cur->next;
		}
		newnode->next = cur->next;
		cur->next->prev = newnode;
		cur->next = newnode;
		newnode->prev = cur;

		num++;
	}
	// 节点删除

	void  ListErase(int pos)
	{
		Node* cur = head;
		Node* prev = NULL;
		assert(pos < num&& pos > 0);
		while (pos--)
		{
			prev = cur;
			cur = cur->next;
		}
		prev->next = cur->next;
		cur->next->prev = prev;
		delete cur;
		num--;
	}

	//返回链表的大小

	int size()
	{
		return num - 1;
	}
	~DList()
	{
		Node* cur = head->next;
		Node* prev = NULL;
		while (cur != head)
		{
			prev = cur;
			cur = cur->next;
			delete prev;
		}
		delete head;
	}
};