CODEWITHSUNDEEP
c#
Tabaraq
Tabaraq

Reputation: 11

How is this code working? Here the class name is used as a datatype in its own implementation

public class Node
{
    public int Value { get; set; }
    public Node Next { get; set; }
}

I am a complete beginner in programming. I decided to learn C# as my first programming language. I came across this code.

How is 'Node' defined as the datatype for Next? It is confusing me a lot.

Upvotes: 1

Views: 232

Answers (4)

Stack Undefined
Stack Undefined

Reputation: 1330

Like other answers, this class represents a node for a linked list. In this case the Node can point to another instance of Node.

Node 
{
   int Value = 1;
   Node Next =============>  Node {
}                                   int Value = 2;
                                    Node Next ===========> Node {
                                  }                                int Value = 3;
                                                                   Node Next =======> null
                                                                 }

You don't usually come across classes having references to themselves like Node.

Upvotes: 1

Joe Sewell
Joe Sewell

Reputation: 6610

This is a good question to ask as you're learning about C#. The key is that there are two kinds of types in C#: "value" types and "reference" types. See this question and its answers for more details.

Because Node is declared as a class, that means it is a reference type. If you make a variable with a reference type, then that variable doesn't hold the data directly; instead, it holds a reference that can point to the data. By default, references have the special value null, which means they don't point to anything. When you assign a variable e.g. myNode.Next = someOtherNode, you don't copy the entirety of someOtherNode to the Next property; you just copy a reference to someOtherNode into the property.

So by the Node class itself having a Node property, a Node object doesn't actually contain another Node object. The first object contains a reference to the second object. This allows one node to point to another node, which can then point to another node, and so on. A collection of nodes organized this way is called a linked list; in this case, it's a linked list of int (32-bit integer) values.

If Node were a value type (declared as a struct instead of a class), then there would indeed be a problem. Value type variables contain the data directly, so you cannot have an instance of a value type which contains another instance of that same value type.

Upvotes: 1

Andrew
Andrew

Reputation: 5277

That looks like a class defining a node in a singly linked list that stores integer values. Remember a class is just a definition of the shape of an object. This may work like:

var node1 = new Node { Value=1} ; node1.Node = new Node { Value=2};

Upvotes: 0

Jonas Høgh
Jonas Høgh

Reputation: 10874

This is called a linked list, an example of a recursive data structure. This can easily be instantiated in C# because the recursion can be ended by letting the last node in the list have a null value for the Next property.

Upvotes: 0

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