模板双向链表

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顺序表和链表几乎是面试必考点，前面我们已经介绍过了模板顺序表(http://blog.csdn.net/ChaseRaod/article/details/70477564)

这篇文章给大家介绍介绍一下模板双向链表

用模板写链表主要还是为了实现代码的类型通用性，以下代码将实现链表的增、删、查、改、判空等操作。

#define _CRT_SECURE_NO_WARNINGS 1#pragma once#include<iostream>#include<stdlib.h>using namespace std;template<class T>//关于节点的模板类struct ListNode{    ListNode(const T& x)//构造函数    :_data(x)    , _next(NULL)    , _prev(NULL){}    T _data;    ListNode<T>* _next;    ListNode<T>* _prev;};template <class T>class List{    typedef ListNode<T> Node;public:    List()        :_head(NULL)        , _tail(NULL){}    List(const List<T>& l)//拷贝构造        :_head(NULL)        , _tail(NULL)    {        Node* cur = l._head;        while (cur)        {            PushBack（cur->_data）;            cur = cur->_next;        }    }    ~List()//析构函数    {        Node* cur = _head;        while (cur)        {            Node* next = cur->_next;            delete cur;            cur = next;        }        _head = _tail = NULL;    }    bool Empty()//判NULL    {        return _head == 0;    }    Node* Find(const T& x)//查找    {        if (_head == NULL)        {            return NULL;        }        int i = 0;        Node* cur = _head;        while (cur)        {            if (cur == x)            {                return cur;            }            cur = cur->_next;        }        return NULL;    }    size_t Size()//大小    {        Node* cur = _head;        int count = 0;        while (cur)        {            count++;            cur = cur->_next;        }        return count;    }    void PushBack(const T& x)//后插    {        if (_head == NULL)//链表为空        {            _head = _tail = new Node(x);        }        else         {            Node* tmp = new Node(x);//开辟一块新的空间            _tail->_next = tmp;            tmp->_prev = _tail;//双向链表            _tail = tmp;        }    }    void PopBack()//后删    {        if (_head == NULL)        {            return;        }        else if (_head == _tail)        {            delete _head;            _head = _tail = NULL;        }        else        {            Node* prev = _tail->_prev;            delete _tail;            _tail = prev;            _tail->_next = NULL;        }    }    void PushFront(const T& x)//前插    {        if (_head == NULL)        {            _head = _tail = new Node(x);        }        else        {            Node* tmp = new Node(x);            _head->_prev = tmp;            tmp->_next = _head;            _head = tmp;        }    }    void PopFront()//前删    {        if (_head == NULL)        {            return;        }        else if (_head == _tail)        {            delete _head;            _head = NULL;        }        else        {            Node* tmp = _head;            _head = _head->_next;            delete _tmp;        }    }    void Insert(Node* pos,const T& x)//指定位置插入    {        assert(pos);        Node* prev = pos->_prev;        Node* next = pos;        Node* cur = new Node(x);        if (prev)        {            prev->_next = cur;            cur->_next = prev;        }        cur->_next = next;        next->_prev = cur;    }    void Erase(Node* pos)//指定位置删除    {        assert(pos);        Node* prev = pos->_prev;        Node* next = pos->_next;        if (_head == NULL)        {            return;        }        if (_head == _tail)        {            delete _head;            _head = _tail = NULL;        }        else if (prev == NULL)        {            Node* cur = _head;            cur = cur->_next;            delete _head;            _head = cur;        }        else if (next == NULL)        {            Node* cur = _tail;            cur = cur->_prev;            delete _tail;            _tail = cur;        }        else        {            prev->_next = next;            next->_prev = prev;            delete pos;        }    }    void Print()//打印    {        Node* cur = _head;        while (cur)        {            cout << cur->_data<< " ";            cur = cur->_next;        }    }    List<int>& operator = (List<T> l)//赋值运算符重载    {        swap(l._head, _head);        swap(l._tail, _tail);        return *this;    }private:     Node* _head;     Node* _tail;};//测试用例void Funteat(){    List<int> l1;    l1.PushBack(1);    l1.PushBack(2);    l1.PushBack(3);    l1.PushBack(4);    l1.Print();}int main(){    Funteat();    system("pause\n");    return 0;}

打印结果如下：
这里写图片描述

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