c++ - 我不明白声明 avl 树时的错误信息

Question

我正在尝试对 AVL 树进行编程，但我遇到了这个我不明白的错误，有人可以帮忙吗？谢谢

source

template<class KeyType, class ItemType>
class AVL
{
 protected:
 template<class KeyType, class ItemType>
 class AVLNode
 {
  public:
  AVLNode(KeyType key, ItemType item) :
  m_Balance(0), m_Depth(0),
  m_Key(key), m_Data(item),
  m_pLeft(0), m_pRight(0)
  {
  }

  KeyType       m_Key;
  ItemType  m_Data;

  AVLNode*  m_pLeft;
  AVLNode*  m_pRight;
  };

  AVLNode<KeyType, ItemType>* m_pRoot;
  public:
  AVL() : m_pRoot(0) { }
  ~AVL() { }
};

Answer 1

尝试进行以下更改:

template<class KeyType, class ItemType>
class AVL
{
 protected:
 // Unnecessary -> template<class KeyType, class ItemType>
 class AVLNode
 {
  public:
     AVLNode(KeyType key, ItemType item) : m_Balance(0), m_Depth(0),
                                           m_Key(key), m_Data(item),
                                           m_pLeft(0), m_pRight(0)
  { }

  private:
     int m_Balance;  // Missing from the ctor declaration
     int m_Depth;  // Missing from the ctor declaration
     KeyType m_Key;
     ItemType m_Data;

     AVLNode<KeyType, ItemType>*  m_pLeft;  // Change here
     AVLNode<KeyType, ItemType>*  m_pRight; // Change here
  };

  AVLNode<KeyType, ItemType>* m_pRoot;
  public:
  AVL() : m_pRoot(0) { }
  ~AVL() { }
};