check all items under a parent node in Visual Basic

Question

I am trying to check all the childnodes under a parent node, the code I have so far only goes about 2-3 levels deep in the TreeView and I am looking to grab all nodes no matter how deep they are. Could someone shed some insight on this.

Below is the code:

Private Sub CheckChildNode(ByVal currNode As TreeNode) 'set the children check status to the same as the current node Dim checkStatus As Boolean = currNode.Checked For Each node As TreeNode In currNode.Nodes node.Checked = checkStatus CheckChildNode(node) Next End Sub

Private Sub CheckParentNode(ByVal currNode As TreeNode) Dim parentNode As TreeNode = currNode.Parent If parentNode Is Nothing Then Exit Sub parentNode.Checked = True For Each node As TreeNode In parentNode.Nodes If Not node.Checked Then parentNode.Checked = False Exit For End If Next CheckParentNode(parentNode) End Sub

Private Sub treeview_AfterCheck(ByVal sender As System.Object, ByVal e As System.Windows.Forms.TreeViewEventArgs) Handles treeview.AfterCheck RemoveHandler treeview.AfterCheck, AddressOf treeview_AfterCheck CheckChildNode(e.Node) CheckParentNode(e.Node) AddHandler treeview.AfterCheck, AddressOf treeview_AfterCheck End Sub

Answer 1

In order to get all subnodes no matter how deep they are, you definitely need recursion.

That is, you take each direct child of a node and do the check for this node. And you also call the method to check subnodes for each child.

So here in Pseudocode.

node getParentNode(node child){
 return child.parent
}

node checkNode(node n){
 // perform check here for node n
 if n is not valid {
  return false!
 }
 // do children recursively
 for each child in n.children{
  // function calls itself!
  checkNode(child)
 }
}

Here's a recursion tutorial for vb.net. Here, here and here is you can find additional information.