Is the LinkedList in .NET a circular linked list?

Question

I need a circular linked list, so I am wondering if LinkedList is a circular linked list?

Answer 1

While the public API of the LinkedList is not circular, internally it actually is. Consulting the reference source, you can see how it's implemented:

// This LinkedList is a doubly-Linked circular list.
internal LinkedListNode head;

Of course, to hide the fact that it's circular, properties and methods that traverse the list make checks to prevent wrapping back to the head.

LinkedListNode:

public LinkedListNode Next {
    get { return next == null || next == list.head? null: next;}
}

public LinkedListNode Previous {
    get { return prev == null || this == list.head? null: prev;}
}

LinkedList.Enumerator:

public bool MoveNext() {
    if (version != list.version) {
        throw new InvalidOperationException(SR.GetString(SR.InvalidOperation_EnumFailedVersion));
    }

    if (node == null) {
        index = list.Count + 1;
        return false;
    }

    ++index;
    current = node.item;   
    node = node.next;  
    if (node == list.head) {
        node = null;
    }
    return true;
}