【C++】模板实现双链表和队列

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首先来了解模板的定义

模板是泛型编程的基础，泛型编程是指编写与类型无关的逻辑代码，是一种复用方式。

模板分为模板函数和模板类

函数模板的格式：

template<class 形参名1，class 形参名2.......class 形参名n>

返回类型函数名（参数列表）

{......}

类模板的格式：

template<class 形参名1，class 形参名2.......class 形参名n>

class 类名

{......}：

template<typename T>struct ListNode{ListNode<T>* _next;ListNode<T>* _prev;T _data;ListNode(const T& d):_next(NULL),_prev(NULL),_data(d){}};

实现模板类

template<typename T>class List{typedef ListNode<T> Node;public:List():_head(NULL), _tail(NULL){}~List(){    Node* cur = _head;while (cur){Node* next = cur->_next;delete cur;cur = next;}_head = _tail = NULL;}List(const List<T>& s):_head(NULL), _tail(NULL){Node* cur = s._head;while (cur){PushBack(cur->_data);cur = cur->_next;}}List<T>& operator=(List<T> s){swap(s._head, _head);swap(s._tail, _tail);return *this;}void PushBack(const T& d){if (_head == NULL){_head = _tail = new Node(d);}else{Node* newnode = new Node(d);_tail->_next = newnode;newnode->_prev = _tail;_tail = newnode;}}void PopBack(){if (_head==NULL){return;}else if (_head == _tail){delete _head;_head = _tail = NULL;}else{Node* cur = _tail->_prev;delete _tail;_tail = cur;_tail->_next = NULL;}}void PushFront(const T& d){if (_head == NULL){_head = _tail = new Node(d);}else{Node* newnode = new Node(d);newnode->_next = _head;_head->_prev = newnode;_head = newnode;}}void PopFront(){if (_head == NULL){return;}else if (_head == _tail){delete _head;_head = _tail = NULL;}else{Node* cur = _head->_next;delete _head;_head = cur;_head->_prev = NULL;}}Node* Find(const T& d){Node* cur = _head;while (cur){if (cur->_data == d){return cur;}cur = cur->_next;}return NULL;}void Insert(const T& d, Node* pos){assert(pos);if (pos == _head){PushFront(d);}else{Node* newnode = new Node(d);Node* prev = pos->_prev;newnode->_next = pos;pos->_prev = newnode;newnode->_prev = prev;prev->_next = newnode;}}void Erase(Node* pos){assert(pos);if (pos == _head){PopFront();}else if (pos == _tail){PopBack();}else{Node* del = pos;Node* prev = pos->_prev;Node* next = pos->_next;prev->_next = next;next->_prev = prev;delete del;del = NULL;}}void Print(){Node* cur = _head;while (cur){cout << cur->_data << " ";cur = cur->_next;}cout << endl;}protected:    Node* _head;    Node* _tail;};

用适配器实现队列

template<class T,class Container>class Queue{public:    void Push(const T& d)    {        _con.PushBack(d);    }    void Pop()    {        _con.PopFront();    }    T& Front()    {        return _con.Front();    }    T& Back()    {        return _con.Back();    }    size_t Size()    {        return _con.Size();    }    bool Empty()    {        return _con.Empty();    }protected:    Container _con;};

在模板类中实现队列中的接口函数

        T& Front(){assert(_head);return _head->_data;}T& Back(){assert(_tail);return _tail->_data;}size_t Size(){size_t count = 0;Node* cur = _head;while (cur){count++;cur = cur->_next;}return count;}bool Empty(){return _head == NULL;}

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