关于双向链表的增删改查和排序的C++实现

#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=0;i<length;i++)    {      Node * temp=new Node();      cout<<"please enter the no"<<i+1<<" 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<=0)    {      cout<<"over stack !"<<endl;      return;    }    for(int i=0;i<position-1;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<=0)    {      cout<<"over stack !"<<endl;      return;    }    for(int i=0;i<position-1;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<=0)    {      cout<<"over stack !"<<endl;      return;    }    for(int i=0;i<position-1;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<=0)    {      cout<<"over stack !"<<endl;      return 0;    }    for(int i=0;i<position-1;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(3);  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(55,1);  l.traverseList();  cout<<"AFTER DELETE-----------------------------------------------------"<<endl;  l.deleteList(1);  l.traverseList();  cout<<"Return Traverse---------------------------------------------"<<endl;  l.traverseListReturn();  cout<<"Find the Second Node's data:"<<l.getItemInList(2)<<endl;  return 0;}