带有头节点的单链表的逆置

#include<iostream>

#include<string>

using namespace std;

/******************这是带有头节点的单链表的逆置××××××××××××××*/

template <class Type>

struct P

{

    Type data;

    P<Type> *next;

};

template <class Type>

class pc

{

    public:

    P<Type> *head;

    P<Type> *tail;

    public:

        void init();

        void show();

        void insert_first();

        void nizhi();

        void destory();

};

template <class Type>

void pc<Type>::init()

{

    head=new P<Type>;

    tail=head;

    cout<<this->head->data<<endl;

    head->next=NULL;

}

template <class Type>

void pc<Type>::show()

{

    if(head==NULL)

    {

        cout<<"链表为空"<<endl;

    }

    else

    {

        P<Type> *link=head->next;

        cout<<"数据为: ";

        while(link)

        {

            cout<<link->data<<" ";

            link=link->next;

        }

        cout<<endl;

    }

}

template <class Type>

void pc<Type>::insert_first()

{

    cout<<"请输入数据"<<endl;

    P<Type> *link=new P<Type>;

    cin>>link->data;

    if(head->next==NULL)

    {

        head->next=link;

        link->next=NULL;

        tail=link;

    }

    else

    {

        head->next=link;

        link->next=tail;

        tail=link;

    }

    show();

}

template <class Type>

void pc<Type>::nizhi()

{

   P<Type> *p1,*p2,*p3;

   p1=head;

   p2=p1->next;

   while(p2)

   {

       p3=p2->next;

       p2->next=p1;

       p1=p2;

       p2=p3;

   }

   head->next=NULL;

   p3=p1;

   cout<<"逆置之后的数据" ;

   while(p1!=head)

   {

      cout<<p1->data<<" ";

      p1=p1->next;

   }

   cout<<endl;

  // return p3;

}

template <class Type>

void pc<Type>::destory()

{

    P<Type> *p1=head;

    while(head)

    {

      head=head->next;

      delete p1;

      p1=head;

    }

    p1=head=NULL;

    if(p1!=NULL||head!=NULL)

    {

        cout<<"内存有问题"<<endl;

    }

}

//template <class Type>

int main()

{

    pc<string> code;

    code.init();

    code.insert_first();

    code.insert_first();

    code.insert_first();

    code.nizhi();

    //code.destory();

//	code.show();

    return 0;

}