Get list of all checked nodes and its subnodes in treeview

Question

I have a treeview list check boxes and the list contains nodes, subnodes and in some cases subnode of subnode. When user check some items i want to get list of selected item

Answer 1

If you like LINQ, you can create an extension method that traverses the whole treeview:

internal static IEnumerable Descendants(this TreeNodeCollection c)
{
    foreach (var node in c.OfType())
    {
        yield return node;

        foreach (var child in node.Nodes.Descendants())
        {
            yield return child;
        }
    }
}

Then you can perform every operations you want using LINQ. In your case, getting a list of selected nodes is easy:

var selectedNodes = myTreeView.Nodes.Descendants()
                    .Where(n => n.Checked)
                    .Select(n => n.Text)
                    .ToList();

An advantage of this approach is it is generic.

However, because the Descendant() method traverses the whole tree, it might be a bit less efficient than the answer given by @mybirthname because it only cares about nodes that are checked with their parents. I dont known if your use case includes this constraint.

EDIT: Now @mybirthname answer has been edited, it is doing the same. Now you have the loop and the LINQ solution, both are recursive.