双向循环链表C++实现

1.单链表：

结构图：

2.双向链表：

3.双向循环链表：

对于本程序中，则是给定一个_head  头结点，而不是指针，因为这样更加方便避免一些空判断问题

/*
版权信息：狼
文件名称：BidCirList.h
文件标识:
文件摘要：
    利用C++实现简单的双向链表功能。增，删，查，改
    //太烦了。。我直接给个 带头结点的  表
    //swap 移花接木已经是个给力的方法。。just try
当前版本：1.1
作    者：狼
完成时间：2015-12-13

*/
#ifndef _BIDCIRLIST_H
#define _BIDCIRLIST_H

#include"afxstd.h"

typedef int DataType;
typedef struct ListNode
{
    ListNode(DataType x=0)
    : _data(x)
    //默认初始化是自环而非  NULL
    , _prev(this)
    , _late(this)
    {}

    DataType _data;
    struct ListNode* _prev;
    struct ListNode* _late;
}ListNode;

class BidCirList
{
public:
    BidCirList()
        :_head(0)
    {}

    BidCirList(DataType *array, size_t n = 0)
        :_head(0)
    {
        size_t i = 0;
        while (n--)
        {
            InsertAter(array[i++]);
        }
    }

    BidCirList(BidCirList & list)
        :_head()
    {
        ListNode* cur = list._head._prev;
        while (cur)
        {
            InsertAter(cur->_data);
            cur = cur->_prev;
            if (cur == &list._head)
                break;
        }
    }

    ~BidCirList()
    {
        Destoty();
    }
    
    BidCirList operator+(BidCirList& list)
    {
        BidCirList tmp(*this);
        ListNode* cur = list._head._prev;

        while (cur != &list._head)
        {
            tmp.InsertAter(cur->_data);
            cur = cur->_prev;
        }
        return tmp;
    }

    BidCirList& operator = (BidCirList& list)
    {
        if (this != &list)
        {
            BidCirList S(list);

            Swap(S);
        }
        return *this;
    }

    //清空空间
    void Destoty()
    {
        ListNode*cur = &_head;
        while (cur->_prev != &_head)
        {
            DelPrev();
        }
    }

    //删除结点之前的结点。默认为头
    void DelPrev(ListNode *del = NULL)
    {
        if (_head._prev == &_head)
            return;
        if (del == NULL)
        {
            //删除头之前
            _head._prev = _head._prev->_prev;
            delete _head._prev->_late;

            _head._prev->_late = &_head;
        }
        else
        {
            del->_prev = del->_prev->_prev;
            delete del->_prev->_late;

            del->_prev->_late = del;
        }
    }

    //删除结点之后一个，，默认为头
    void DelLate(ListNode *del = NULL)
    {
        if (_head._prev == &_head)
            return;
        if (del == NULL)
        {
            _head._late = _head._late->_late;
            delete _head._late->_prev;

            _head._late->_prev = &_head;
        }
        else
        {
            del->_late = del->_late->_late;
            delete del->_late->_prev;

            del->_late->_prev = del;
        }
    }

    //在结点之前插入,默认为头
    void InsertAter(DataType x ,ListNode* ins= NULL)
    {
        ListNode* tmp = new ListNode(x);

        if (ins == NULL)
        {
            tmp->_prev = &_head;
            tmp->_late = _head._late;

            tmp->_late->_prev = tmp;
            tmp->_prev->_late = tmp;
        }
        else
        {
            tmp->_prev = ins;
            tmp->_late = ins->_late;

            tmp->_late->_prev = tmp;
            tmp->_prev->_late = tmp;
        }
    }

    ListNode* Find(DataType x)
    {
        ListNode* cur = _head._prev;
        while (cur)
        {
            if (cur == &_head)
                return NULL;
            if (cur->_data == x)
            {
                return cur;
            }
            cur = cur->_prev;
        }
    }

    void Erase(ListNode * node)
    {
        if (node == &_head)
        {
            return;
        }
        else
        {
            ListNode* tmp = node;
            node->_prev->_late = node->_late;
            node->_late->_prev = node->_prev;
            delete tmp;
            tmp = NULL;
        }
    }

    //反向打印
    void PrintPrev()
    {
        ListNode* cur = _head._prev;
        while (cur)
        {
            if (cur == &_head)
                break;
            cout << cur->_data << " -> ";
            cur = cur->_prev;
        }
        cout << " Over! " << endl;
    }
    //正向打印
    void PrintLate()
    {
        ListNode* cur = _head._late;

        while (cur)
        {
            if (cur == &_head)
                break;
            cout << cur->_data << " -> ";
            cur = cur->_late;
        }
        cout << " Over! " << endl;
    }

    void Swap(BidCirList &list)
    {
        ::swap(_head._prev->_late, list._head._prev->_late);
        ::swap(_head._prev, list._head._prev);

        ::swap(_head._late->_prev, list._head._late->_prev);
        ::swap(_head._late, list._head._late);

    }
    
private:
    ListNode _head;
};

#endif