Iterator for template binary tree

Question

I write template class for binary tree:

template <class T>
class Tree {
public:
    Tree():head_(NULL),size_(0){}
    ~Tree();
    bool isEmpty()const {return size_ == 0;};
    bool insert(const T& ele);
    bool remove(const T& ele);
    size_t size() {return size_;} 
public:

    class inorder_iterator 
    {
        inorder_iterator& operator++ ();
    private:
        Node<T>* cur_;
    };
}

What is the defintion for operator++?(I can`t compile using the following)

template <class T>
Tree<T>::inorder_iterator& 
Tree<T>::inorder_iterator::operator++ ()
{
    //....
}

Does the third line of the second snippet start with Tree>T> in your source code? — Alexander Pavlov
– Alexander Pavlov, Commented Feb 24, 2012 at 16:25

piokuc · Accepted Answer · 2012-02-24 16:56:20Z

2

With these changes it compiles:

template <class T>
class Node {}; 

template <class T>
class Tree {
    Node<T> head_;
    size_t size_;
public:
    Tree():head_(NULL),size_(0){}
    ~Tree();
    bool isEmpty()const {return size_ == 0;};
    bool insert(const T& ele);
    bool remove(const T& ele);
    size_t size() {return size_;} 
public:

    class inorder_iterator 
    {   
        inorder_iterator& operator++ (); 
    private:
        Node<T>* cur_;
    };  
};

template <class T>
typename Tree<T>::inorder_iterator& 
Tree<T>::inorder_iterator::operator++ ()
{
    //....
}

edited Feb 24, 2012 at 16:56

answered Feb 24, 2012 at 16:48

piokuc

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2 Comments

YAKOVM Over a year ago

Can you pls explain the need of typename key?

piokuc Over a year ago

This is because of dependent scope of Tree<T> in the return type of the function, here is a good explanation: stackoverflow.com/questions/6571381/…

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