C # Ring Linked List

Question

It was necessary to implement a ring list. Made through extension methods. But there is one nuance. How to implement the return from the method of the first value in the node? In this case, I always return the second value ("Tanya") at the first pass, then after the last node, the transition to the first value.

class Program { static void Main(string[] args) { // Создадим связный список LinkedList<string> linkedList = new LinkedList<string>(); // Добавим несколько элементов linkedList.AddFirst("Вася"); linkedList.AddFirst("Петя"); linkedList.AddFirst("Таня"); linkedList.AddFirst("Коля"); // Отобразим элементы в прямом направлении LinkedListNode<string> node; Console.WriteLine("Элементы коллекции в прямом направлении: "); for (node = linkedList.First; node != null; node = node.Next) Console.Write(node.Value + "\t"); Console.WriteLine(); var result = GetValue(linkedList.First); Console.WriteLine($"+++++++ {result} ++++++++"); Console.ReadKey(); } private static string GetValue(LinkedListNode<string> node) { node = CircularLinkedList.NextOrFirst(node); return node.Value; } }

Extension method for a single-linked list:

  public static class CircularLinkedList { public static LinkedListNode<T> NextOrFirst<T>(this LinkedListNode<T> current) { return current.Next ?? current.List.First; } public static LinkedListNode<T> PreviousOrLast<T>(this LinkedListNode<T> current) { return current.Previous ?? current.List.Last; } }

, so Kolya has Next, which is Tanya, because you see Tanya instead of Kolya
Yes, I understand that and I did it to get the next node, I need to make some condition that I first return First from the method, and only then Next.

Accepted Answer · 2018-09-26T13:11:56

The GetValue method has an incorrect name:

 private static string GetNextCircularValue(LinkedListNode<string> node) { node = CircularLinkedList.NextOrFirst(node); return node.Value; }

Perhaps you wanted to do the following:

 private static string GetValueAndAdvance(ref LinkedListNode<string> node) { string result = node.Value; node = CircularLinkedList.NextOrFirst(node); return result; } node = linkedList.First; var result = GetValueAndAdvance(ref node);

@JDo To get insight into the essence of my answers over them should be meditated).
string GetValueAndAdvance(ref LinkedListNode<string> node);

Grundy grundy 58.6k 7 53 94 · Answer 2 · 2018-09-27T07:16:56

Since in this code

 private static string GetValue(LinkedListNode<string> node) { node = CircularLinkedList.NextOrFirst(node); return node.Value; }

first the next element is obtained, and only then the value is taken; when the first element is transmitted, the value will be obtained from the next one.

To solve, it is enough to transmit not the first element, but the last one:

 var result = GetValue(linkedList.Last);

@JDo, instead of getting the value, it was better to get the next item, and get the value through the usual Value property
@JDo, well, I already did extensions, it was worth using it as: node = node.NextOrFirst();

C # Ring Linked List

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