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

I know this thread is quite old and my method doesn't exactly reduce the amount of recursion and it may be slightly slower but it makes my code a bit cleaner.

I use an extension method for IEnumarable<> to flatten any tree (not just TreeView nodes):

public static IEnumerable Flatten(
    this IEnumerable rootNodes, 
    Func> childrenFunction)
{
    return rootNodes.SelectMany(
        child => new[] { child }
            .Concat((childrenFunction(child) ?? Enumerable.Empty())
            .Flatten(childrenFunction)));
}

I then use this method to get all the nodes of the tree:

IEnumerable allNodes = treeView1.Nodes.Cast()
    .Flatten(n => n.Nodes.Cast());