双向链表的创建，插入，查找，删除，正序，逆序

实现双向链表的插入，查找(通过位置返回结点)，删除(删指定位置的结点)，正序，逆序的输出。

#include<iostream>
 
 using namespace std;
 
 class Node          //组成双向链表的节点
 {
 public:
     int data;
     Node * pNext;
     Node * pLast;
 };
 
 class List      //构造一个双向链表
 {
 private:
     Node * pHead;
     Node * pTail;
     int length;
 public:
     List(int length)　　　　//创建双向链表
     {
         this->length=length;
         pHead=new Node();
         pHead->pLast=NULL;
         pTail=pHead;
         for(int i=;i<length;i++)
         {
             Node * temp=new Node();
             cout<<"please enter the no"<<i+<<" Node's data:";
             cin>>temp->data;
             temp->pNext=NULL;
             temp->pLast=pTail;
             pTail->pNext=temp;
             pTail=temp;
         }
     }
 
     void traverseList()　　　　//正向遍历
     {
         Node * p=pHead->pNext;
         while(p!=NULL)
         {
             cout<<p->data<<endl;
             p=p->pNext;
         }
     }
 
     void traverseListReturn()　　　　//逆向遍历
     {
         Node * p=pTail;
         while(p->pLast!=NULL)
         {
             cout<<p->data<<endl;
             p=p->pLast;
         }
     }
 
     void sortList()     //冒泡排序
     {
         Node * p=new Node();
         Node * q=new Node();
         int temp;
         for(p=pHead->pNext;p->pNext!=NULL;p=p->pNext)
         {
             for(q=p->pNext;q!=NULL;q=q->pNext)
             {
                 if(q->data<p->data)
                 {
                     temp=q->data;
                     q->data=p->data;
                     p->data=temp;
                 }
             }
         }
     }
 
     void sortListByInsertWay()        //插入排序
     {
         if(pHead->pNext==NULL||pHead->pNext->pNext==NULL)
         {
             return;
         }
         Node * p2=pHead->pNext->pNext;
         Node * p1=pHead;
         pHead->pNext->pNext=NULL;
         while(p2)
         {
             Node * pN=p2->pNext;
             while(p1->pNext)
             {
                 if(p2->data<p1->pNext->data)
                 {
                     p2->pNext=p1->pNext;
                     p2->pLast=p1;
                     p1->pNext->pLast=p2;
                     p1->pNext=p2;
                     break;
                 }
                 p1=p1->pNext;
             }
             if(p1->pNext==NULL)
             {
                 p2->pNext=NULL;
                 p2->pLast=p1;
                 p1->pNext=p2;
             }
             p2=pN;
         }
 
         //重新查找pTail的位置
         Node * pt=pHead;
         while(pt->pNext)
         {
             pt=pt->pNext;
         }
         pTail=pt;
     }
 
     void changeList(int num,int position)　　　　//修改链表中指定位置的节点
     {
         Node * p=pHead->pNext;
         if(position>length||position<=)
         {
             cout<<"over stack !"<<endl;
             return;
         }
         for(int i=;i<position-;i++)
         {
             p=p->pNext;
         }
         p->data=num;
     }
 
     void insertList(int num,int position)　　　　//插入数据
     {
         Node * p=pHead->pNext;
         if(position>length||position<=)
         {
             cout<<"over stack !"<<endl;
             return;
         }
         for(int i=;i<position-;i++)
         {
             p=p->pNext;
         }
         Node * temp=new Node();
         temp->data=num;
         temp->pNext=p;
         temp->pLast=p->pLast;
         p->pLast->pNext=temp;
         p->pLast=temp;
         length++;
     }
 
     void clearList()　　　　　　//清空
     {
         Node * q;
         Node * p=pHead->pNext;
         while(p!=NULL)
         {
             q=p;
             p=p->pNext;
             delete q;
         }
         p=NULL;
         q=NULL;
     }
 
     void deleteList(int position)　　　//删除指定位置的节点
     {
         Node * p=pHead->pNext;
         if(position>length||position<=)
         {
             cout<<"over stack !"<<endl;
             return;
         }
         for(int i=;i<position-;i++)
         {
             p=p->pNext;
         }
         p->pLast->pNext=p->pNext;
         p->pNext->pLast=p->pLast;
         delete p;
         length--;
     }
 
     int getItemInList(int position)　　　　　　//查找指定位置的节点
     {
         Node * p=pHead->pNext;
         if(position>length||position<=)
         {
             cout<<"over stack !"<<endl;
             return ;
         }
         for(int i=;i<position-;i++)
         {
             p=p->pNext;
         }
         return p->data;
     }
 
     ~List()
     {
         Node * q;
         Node * p=pHead->pNext;
         while(p!=NULL)
         {
             q=p;
             p=p->pNext;
             delete q;
         }
         p=NULL;
         q=NULL;
     }
 
 };
 
 int main()
 {
     List l();
     l.traverseList();
     cout<<"AFTER SORT------------------------------------------------------"<<endl;
 //    l.sortList();             //冒泡排序
     l.sortListByInsertWay();    //插入排序
     l.traverseList();
     cout<<"AFTER INSERT-----------------------------------------------------"<<endl;
     l.insertList(,);
     l.traverseList();
     cout<<"AFTER DELETE-----------------------------------------------------"<<endl;
     l.deleteList();
     l.traverseList();
     cout<<"Return Traverse---------------------------------------------"<<endl;
     l.traverseListReturn();
     cout<<"Find the Second Node's data:"<<l.getItemInList()<<endl;
     return ;
 }