1

So I have a generic class Node<T> which looks like this. It just hold the value and the reference to the next Node<T>

public class Node<T>
{
    public T Value { get; set; }
    public Node<T> Next { get; set; }

    // Some Methods go here
}

There's another class called CustomLinkedList<T> which looks like this

public class CustomLinkedList<T> : IEnumerable<T>
{
    Node<T> m_first;
    Node<T> m_current;
    int m_length;

    public CustomLinkedList()
    {
        m_first = new Node<T>();
        m_current = m_first;
        m_length = 0;
    }

    // Adding, removing and other methods go here
}

Baisically CustomLinkedList<T> is the collection of Node<T>s. This is just a challenge to myself to build a collection like LinkedList<T> (At least what I think of it to be). The code bellow shows the example of how I implemented the adding functionality.

public void AddLast(T value)
{
    m_current.Value = value;
    m_current.Next = new Node<T>();
    m_current = m_current.Next;
    m_length++;
}

public void AddFirst(T value)
{
    Node<T> newFirst = new Node<T>();
    newFirst.Value = value;
    newFirst.Next = m_first;
    m_first = newFirst;
    m_length++;
}

There are also AddAfter() and AddBefore() methods alongside with some RemoveXXX() methods. So I wanted CustomLinkedList<T> to implement IEnumerable<T> and my GetEnumerator() method looks like this

public IEnumerator<T> GetEnumerator()
{
    if (m_length > 0)
    {
        Node<T> nodeToReturn = m_first;
        for (int i = 0; i < m_length; i++)
        {
            if (nodeToReturn == null)
                break;
            yield return nodeToReturn.Value;
            nodeToReturn = nodeToReturn.Next;
        }
    }
}

But the compiler complains about following

CustomGenericCollections.CustomLinkedList<T>' does not implement interface member 'System.Collections.IEnumerable.GetEnumerator()'. 'CustomGenericCollections.CustomLinkedList<T>.GetEnumerator()' cannot implement 'System.Collections.IEnumerable.GetEnumerator()' because it does not have the matching return type of 'System.Collections.IEnumerator'.

I can't figure out what is the problem.

Dimitri
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1 Answers1

4

Because IEnumerable<T> inherits from IEnumerable, you need to implement the non-generic GetEnumerator() as well. Add this to your class:

IEnumerator IEnumerable.GetEnumerator()
{
    return this.GetEnumerator();
}
Magnus Grindal Bakken
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