To find the penultimate node of a linked list

Recently read a book on the list of the last nth node, a simple implementation of the list, the implementation of the scheme is as follows

1, not through the chain table length sequence to traverse the reciprocal nth node Getreserven is so implemented.

2, of course, if the link table records the length of the node can also be directly sequence traversal of the first LENTH-N node is the reciprocal node.

Template<class t> class Linkedlist{public:operator T () {return m_data;}    Virtual ~linkedlist () {if (m_size!=0) Clear ();        } void AddData (T data) {if (m_size==0) {m_data=data;            } else {linkedlist<t>* ptem=new linkedlist<t>;            Ptem->m_data=data;            Ptem->m_pprev=this->m_ptail;            ptem->m_pnext=0;            this->m_ptail->m_pnext=ptem;        this->m_ptail=ptem;    } m_size++;    } void SetData (T data) {m_data=data;        } void Clear () {linkedlist<t>*ptem=this->next ();        linkedlist<t>*pdel;        for (; Ptem;)            {Pdel=ptem;            Ptem=ptem->next ();        Delete Pdel;        } m_ptail=this;        M_pprev=this;    m_size=0;    } int Size () {return m_size;    } T GetData () {return m_data; } LinkeDlist<t>*next () {return m_pnext;    } linkedlist<t>*gettail () {return m_ptail;    } linkedlist<t>*getprevious () {return m_pprev; } linkedlist<t>* Getreserven (int n) {if (n>m_size| |        N<=0) return 0;        linkedlist<t>*pfront=this;        linkedlist<t>*pbehand=this;        for (int i=1; i<=n; i++) {pbehand=pbehand->next ();            } while (true) {if (pbehand==0) return pfront;            Pbehand=pbehand->next ();        Pfront=pfront->next ();    }} static linkedlist<t>* CreateList () {return new linkedlist<t>;        };p rivate:linkedlist (): M_pnext (0), M_pprev (0), M_ptail (0), m_size (0) {m_ptail=this;    M_pprev=this;    } linkedlist<t>*m_pnext;    linkedlist<t>*m_ptail;    linkedlist<t>*m_pprev;    int m_size; T m_data;};

The test code is as follows

#include <iostream> #include <string> #include "LinkedList.h" using namespace Std;int Main () {    Linkedlist<string> *ptem=linkedlist<string>::createlist ();    Ptem->adddata ("xxx");    Ptem->adddata ("Dsdf");    Ptem->adddata ("DFSD");    Ptem->adddata ("dseee");    Ptem->adddata ("xxxx");    Ptem->adddata ("DSFDSF");    Ptem->adddata ("FDSFD");    Linkedlist<string>*p=ptem;    for (; p;)    {        cout<<p->getdata () << ",";        P=p->next ();    }    cout<<endl;    Linkedlist<string>*pdata=ptem->getreserven (5);    if (pData)      cout<< "reserve N:" <<pdata->getdata () <<endl;    else{      cout<< "Reserver not Found!" <<endl;    }    return 0;}

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Count the nth nodes of the linked list