Accessing all the nodes in TreeView Control

Question

I have a TreeView Control with set of nodes and child nodes. For example:

ROOT has A,B,C.

A has a1, a2, a3 and then

Answer 1

You can create an Extension Method that returns a List.

Descendants Extension Method

using System.Linq;
using System.Windows.Forms;
using System.Collections.Generic;

public static class Extensions
{
    public static List Descendants(this TreeView tree)
    {
        var nodes = tree.Nodes.Cast();
        return nodes.SelectMany(x => x.Descendants()).Concat(nodes).ToList();
    }

    public static List Descendants(this TreeNode node)
    {
        var nodes = node.Nodes.Cast().ToList();
        return nodes.SelectMany(x => Descendants(x)).Concat(nodes).ToList();
    }
}

To get all nodes of a TreeView

var nodes = this.treeView1.Descendants();

To get all child nodes of a Node

var nodes = this.treeView1.Nodes[0].Descendants();

You can also use linq to search between nodes.

Ancestors Extension Method

To get ancestors of a node, you may also me interested to Ancestors extension methods.