c++ - 错误 1 ​​错误 C2665 : 'DoublyListIterator::DoublyListIterator' : none of the 2 overloads could convert all the argument types

Question

我正在制作一个双向链表。错误与我的 getIterator 方法有关。我想不通。有谁知道吗？

Here is where the error is?
    // ------------------------------------------------------------------------------
    //  Name:           GetIterator
    //  Description:    Generates an iterator pointing towards the current head node
    //  Arguments:      None.
    //  Return Value:   <Datatype> Iterator
    // ------------------------------------------------------------------------------
    DoublyListIterator<Datatype> getIterator()
    {
        return DoublyListIterator<Datatype>(this, m_head);
    }
};

#ifndef DOUBLYLINKEDLIST_H
#define DOUBLYLINKEDLIST_H

#include <iostream>
#include <fstream>
#include <iomanip>
#include <string>
using namespace std;

template<class Datatype> class DoublyListNode;
template<class Datatype> class DoublyLinkedList;
template<class Datatype> class DoublyListIterator;

// -------------------------------------------------------
// Name:        DListNode
// Description: This is the Doubly-linked list node class.
// -------------------------------------------------------
template<class Datatype>
class DListNode
{
public:
    Datatype m_data;
    DListNode<Datatype>* m_next;
    DListNode<Datatype>* m_prev;

    // ----------------------------------------------------------------
    //  Name:           InsertAfter
    //  Description:    This adds a node after the current node.
    //  Arguments:      p_data - The data to store in the new node.
    //  Return Value:   None.
    // ----------------------------------------------------------------
    void InsertAfter(Datatype p_data)
    {
        // create the new node.
        DListNode<Datatype>* newNode= new DListNode<Datatype>;
        newNode->m_data = p_data;
        // make the new node point to the next node.
        newNode->m_next = m_next;
        newNode->m_prev = this;

        // make the node before it, point to the new node
        if(m_next != 0)
            m_next->m_prev= newNode;

        m_next = newNode;
    }
    // ----------------------------------------------------------------
    //  Name:           InsertBefore
    //  Description:    This adds a node before the current node.
    //  Arguments:      p_data - The data to store in the new node.
    //  Return Value:   None.
    // ----------------------------------------------------------------
    void InsertBefore(Datatype p_data)
    {
        //Create new Node
        DListNode<Datatype>* newNode = new DListNode<Datatype>;
        newNode->m_data = p_data;
        //Set up new Node Pointers
        newNode->m_next = this;
        newNode->m_prev = m_prev;
        //if theres a node before it, make it point to new node
        if(m_prev != 0)
            m_prev->m_next = newNode;

        m_prev = newNode;
    }
};
// -------------------------------------------------------------
// Name:        DLinkedList
// Description: This is the Doubly-linked list container class.
// -------------------------------------------------------------
template<class Datatype>
class DoublyLinkedList
{
public:
    DListNode<Datatype>* m_head;
    DListNode<Datatype>* m_tail;
    int m_count;

    // -----------------------------------------------------------------------------------------
    //  Name:           DLinkedList
    //  Description:    Constructor, creates a head node, tail node & a count.
    //  Arguments:      m_head: the head node of the list.
    //                  m_tail: the tail node of the list.
    //  Return Value:   None.
    // -----------------------------------------------------------------------------------------
    DoublyLinkedList()
    {
        m_head= 0;
        m_tail= 0;
        m_count= 0;
    }

    // -----------------------------------------------------------------------------------------
    //  Name:           ~DLinkedList
    //  Description:    Destructor, creates a pointer for the head node,
    //                  deletes the value in the list and iterates.
    //  Arguments:      m_head: the head node of the list.
    //                  itr:    moves through the list.
    //  Return Value:   None.
    // -----------------------------------------------------------------------------------------
    ~DoublyLinkedList()
    {
        // temporary node pointers.
        DListNode<Datatype>* itr= m_head;
        DListNode<Datatype>* next;
        while(itr != 0)
        {
            // save the pointer to the next node.
            next = itr->m_next;
            // delete the current node.
            delete itr;
            // make the next node the current node.
            itr= next;
        }
    }
    // ----------------------------------------------------------------
    //  Name:           Length
    //  Description:    Gets the size of the list
    //  Arguments:      None.
    //  Return Value:   size of the list.
    // ----------------------------------------------------------------
    int Length()
    {
        return m_count;
    }
    // -------------------------------------------------------------------------------------
    //  Name:           Append
    //  Description:    This adds a node to the end of the list, then points to the newNode
    //  Arguments:      p_data - The data to store in the new node.
    //                  m_count is increased.
    //  Return Value:   None.
    // -------------------------------------------------------------------------------------
    void Append(Datatype p_data)
    {
        if(m_head == 0)
        {
            // create a new head node.
            m_head= m_tail= new DListNode<Datatype>;
            m_head->m_data= p_data;
            m_head->m_next= 0;
            m_head->m_prev= 0;
        }
        else
        {
            // insert a new node after the tail and reset the tail.
            m_tail->InsertAfter(p_data);
            m_tail= m_tail->m_next;
        }
        m_count++;
    }
    // -----------------------------------------------------------------------------------
    //  Name:           Prepend
    //  Description:    This adds a node before the head node, then points to the newNode
    //  Arguments:      p_data - The data to store in the new node.
    //                  m_count is increased.
    //  Return Value:   None.
    // -----------------------------------------------------------------------------------
    void Prepend(Datatype p_data)
    {
        // create the new node.
        DListNode<Datatype>* newNode= new DListNode<Datatype>;
        newNode->m_data= p_data;

        newNode->m_next= m_head;
        // set the head node and the tail node if needed.
        m_head= newNode;
        if(m_tail== 0)
            m_tail= m_head;
        m_count++;
    }
    // ----------------------------------------------------------------------------------------------------------------
    //  Name:           Insert
    //  Description:    Inserts data before the iterator, this works whether the iterator is backwards of forwards
    //                  through the list.Inserts at the end of the list if iterator is invalid.
    //  Arguments:      p_iterator: The iterator to insert before
    //                  p_data: the data to insert
    //  Return Value:   None.
    // ----------------------------------------------------------------------------------------------------------------
    void Insert(DoublyListIterator<Datatype>& p_itr, Datatype p_data)
    {
        if(p_itr.m_node != 0)
        {
            // insert the data before the iterator
            p_itr.m_node->InsertBefore(p_data);

            //if the iterator was at the head of the list,
            //reset the head pointer
            if(p_itr.m_node == m_head)
            {
                m_head = m_head->m_prev;
            }
            // increment the count
            m_count++;
        }
        else
        {
            Append(p_data);
        }
    }

    // -------------------------------------------------------------------------------------------------------
    //  Name:           Remove
    //  Description:    Removes the node that the iterator points to, moves iterator forward to the next node.
    //  Arguments:      p_iterator: The iterator to remove
    //                  isForward: Tells which direction the iterator was going through the list
    //  Return Value:   None.
    // -------------------------------------------------------------------------------------------------------
    void Remove(DoublyListIterator<Datatype>& p_itr, bool isForward)
    {
        // temporary node pointer.
        DListNode<Datatype>* newNode;

        // if node is invalid, do nothing.
        if(p_itr.m_node == 0)
            return;

        // save the pointer to the node we want to delete.
        newNode = p_itr.m_node;

        // if the node we want to remove is the head or the tail
        // nodes, then move the head or tail to the next or
        // previous node.
        if(newNode == m_head)
        {
            m_head = m_head->m_next;
        }
        else if(newNode == m_tail)
        {
            m_tail = m_tail->m_prev;
        }
        // if moving from head to tail, move the iterator forward 
        // to the next valid node
        if(isForward == true)
        {
            p_itr.Forth();

        }
        //else, we are moving from tail to head, so move the iterator
        // to the previous valid node
        else
        {
            p_itr.Back();
        }

        if(newNode->m_prev != 0)
            newNode->m_prev->m_next = newNode->m_next;
        else if(newNode->m_next != 0)
            newNode->m_next->m_prev = newNode->m_prev;
        // delink and delete the node.
        delete newNode;

        // if the head is 0, then set the tail to 0 as well.
        if(m_head == 0)
            m_tail = 0;

        m_count--;


    }
    // -----------------------------------------------------------------------------------
    //  Name:           RemoveHead
    //  Description:    Removes the Head of the List and points to the New Node
    //  Arguments:      None
    //  Return Value:   None.
    // -----------------------------------------------------------------------------------
    void RemoveHead()
    {
        DListNode<Datatype>* newNode = 0;
        if(m_head!= 0)
        {
            // make node point to the next node.
            newNode = m_head->m_next;
            // then delete the head and make the pointer
            // point to node.
            delete m_head;
            m_head= newNode;
            // if the head is null, then you’ve just deleted the only node
            // in the list. set the tail to 0.
            if(m_head== 0)
                m_tail= 0;
            m_count--;
        }
    }

    // -----------------------------------------------------------------------------------------
    //  Name:           RemoveTail
    //  Description:    The tail node is removed - but at a much slower pace than the head node, 
    //  this is because the node has to search through the list to find the node before the tail
    //  node and set it to the new tail node then deleting the tail node
    //  Arguments:      None.
    //  Return Value:   None.
    // -----------------------------------------------------------------------------------------
    void RemoveTail()
    {
        DListNode<Datatype>* newNode = m_head;
        // if the list isn’t empty, then remove a node.
        if(m_head!= 0)
        {
            // if the head is equal to the tail, then
            // the list has 1 node, and you are removing it.
            if(m_head == m_tail)
            {
                // delete the node and set both pointers
                // to 0.
                delete m_head;
                m_head= m_tail= 0;
            }
            else
            {
                // skip ahead until you find the node
                // right before the tail node
                while(newNode->m_next!= m_tail)
                    newNode = newNode->m_next;
                // make the tail point to the node before the
                // current tail and delete the old tail.
                m_tail= newNode;
                delete newNode->m_next;
                newNode->m_next= 0;
            }
            m_count--;
        }
    }

    // ------------------------------------------------------------------------------
    //  Name:           GetIterator
    //  Description:    Generates an iterator pointing towards the current head node
    //  Arguments:      None.
    //  Return Value:   <Datatype> Iterator
    // ------------------------------------------------------------------------------
    DoublyListIterator<Datatype> getIterator()
    {
        return DoublyListIterator<Datatype>(this, m_head);
    }
};
// ----------------------------------------------------------
// Name:        DoublyListIterator
// Description: This is the basic linked list iterator class.
// ----------------------------------------------------------
template<class Datatype>
class DoublyListIterator
{
public:
    // ----------------------------------------------------------------
    //  Name:           m_node
    //  Description:    pointer to the current node
    // ----------------------------------------------------------------
    DoublyListNode<Datatype>* m_node;

    // ----------------------------------------------------------------
    //  Name:           m_list
    //  Description:    pointer to the current list.
    // ----------------------------------------------------------------
    DoublyLinkedList<Datatype>* m_list;

    // -----------------------------------------------------------------------------------------
    //  Name:           DListIterator
    //  Description:    Constructor, creates an iterator that points to the given list and node.
    //  Arguments:      p_list: pointer to the list the iterator belongs to.
    //                  p_node: pointer to the current node.
    //  Return Value:   None.
    // -----------------------------------------------------------------------------------------
    DoublyListIterator(DoublyLinkedList<Datatype>* p_list= 0, DoublyListNode<Datatype>* p_node= 0)
    {
        m_list= p_list;
        m_node= p_node;
    }

    // ------------------------------------------------------------------
    //  Name:           Start
    //  Description:    Resets the iterator to the beginning of the list.
    //  Arguments:      None.
    //  Return Value:   None.
    // ------------------------------------------------------------------
    void Start()
    {
        if(m_list!= 0)
            m_node= m_list->m_head;
    }

    // ----------------------------------------------------------------
    //  Name:           End
    //  Description:    Resets the iterator to the end of the list
    //  Arguments:      None.
    //  Return Value:   None.
    // ----------------------------------------------------------------
    void End()
    {
        if(m_list!= 0)
            m_node = m_list->m_tail;
    }

    // ----------------------------------------------------------------
    //  Name:           Forth
    //  Description:    Moves the iterator forward by one position
    //  Arguments:      None.
    //  Return Value:   None.
    // ----------------------------------------------------------------
    void Forth()
    {
        if(m_node!= 0)
            m_node= m_node->m_next;
    }

    // ----------------------------------------------------------------
    //  Name:           Back
    //  Description:    Moves the iterator backward by one position.
    //  Arguments:      None.
    //  Return Value:   None.
    // ----------------------------------------------------------------
    void Back()
    {
        if(m_node!= 0)
            m_node = m_node->m_prev;
    }

    // ----------------------------------------------------------------
    //  Name:           Item
    //  Description:    Gets the item that the iterator is pointing to.
    //  Arguments:      None.
    //  Return Value:   Reference to the data in the node.
    // ----------------------------------------------------------------
    Datatype& Item()
    {
        return m_node->m_data;
    }

    // ----------------------------------------------------------------
    //  Name:           Valid
    //  Description:    Determines if the node is valid.
    //  Arguments:      None.
    //  Return Value:   true if valid
    // ----------------------------------------------------------------
    bool Valid()
    {
        return (m_node!= 0);
    }
    // ----------------------------------------------------------------
    //  Name:           operator==
    //  Description:    Determines if two iterators point to the same node.
    //  Arguments:      None.
    //  Return Value:   true if they point to the same node.
    // ----------------------------------------------------------------
    bool operator==( DoublyListIterator<Datatype>& p_rhs )
    {
        if( m_node == p_rhs.m_node && m_list == p_rhs.m_list )
        {
            return true;
        }
        return false;
    }
};
#endif

如果需要更多代码，请询问。我不想在 Stack overflow 用户上放置大量代码。

Answer 1

您的意思是将您的类命名为 DoublyListNode 而不是 DListNode 吗？

你转发声明

template<class Datatype> class DoublyListNode;

但你定义

template<class Datatype>
class DListNode

并使用成员

DListNode<Datatype>* m_head;
DListNode<Datatype>* m_tail;

在列表中，但迭代器接受参数:

DoublyListIterator(DoublyLinkedList<Datatype>* p_list= 0, DoublyListNode<Datatype>* p_node= 0)

回顾一下，DoublyLinkedList 中的成员是一个 DListNode，但是 DoublyListIterator 的构造函数需要一个 DoublyListNode .

选择一个名字并坚持下去。