循环链表的操作

#include <iostream>

using namespace std;
class DLLnode{

public:
    int data;
    DLLnode *prev;
    DLLnode *next;
    DLLnode(int value,DLLnode *p=NULL,DLLnode *n=NULL)
    {
        data=value;
        prev=p;
        next=n;
    }
    DLLnode(DLLnode *p=NULL,DLLnode *n=NULL)
    {

        prev=p;
        next=n;
    }
};
class DList{
public:
    int size;
    DLLnode *head;
    DLLnode *tail;
    DLLnode *current;
    DList()
    {
        size=0;
        head=new DLLnode(0,NULL,NULL);
        tail=head;
        current=head;
    }
    ~DList()
    {
        clear();

    }
    void clear()
    {
        while(head!=head)
        {
            DLLnode *temp=head->next;
            delete head;
            head=temp;
        }
        size=0;
        tail=NULL;

    }
    void addtoFront(int value)
    {
        DLLnode *a;
        a=new DLLnode(value);
        a->prev=head;
        a->next=head->next;
        head->next->prev=a;
        head->next=a;
        size++;
    }
    void addtoTail(int value)
    {
        DLLnode *a;
        a=new DLLnode(value);
        current->next=a;
        a->prev=current;
        a->next=head;
        current=a;
        size++;


    }
    bool deleteFixvalue(int value)
    {
        DLLnode *cur=head->next;
        while(cur->data!=value)
        {
            cur=cur->next;
            if(cur==head)
            {
                cout<<"未找到该元素"<<endl;
                return false;
            }
        }
        cur->prev->next=cur->next;
        cur->next->prev=cur->prev;
        delete[]cur;
       return true;

    }
    void prt_list()
    {
        DLLnode *p=head->next;
        while (p!=head)
        {
            cout<<p->data<<endl;
            p=p->next;
        }
    }
};
;