Treeview Traversing

i have a class:

VB Code:

Public Class FilesFoldersList
    Inherits Windows.Forms.TreeView
    Public Quit As Boolean = False
    Public Function FindNode(ByVal TNC As TreeNodeCollection, ByVal Text As String) As Windows.Forms.TreeNode
        Dim TN As TreeNode
        For Each TN In TNC
            If Quit = True Then Exit Function
            Debug.WriteLine(TN.Text)
            If TN.Text = Text Then
                FindNode = TN
                Quit = True
                Exit Function
            End If
            FindNode(TN.Nodes, Text)
        Next
 
    End Function
End Class

which i use to find a certain node in a treeview, and this is how i use it:

VB Code:

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim TN As TreeNode
        TN = FFList.FindNode(FFList.Nodes, "C:\timem")
        MsgBox(TN.Text)
    End Sub

the FindNodes function works, but it won't return anything. I checked everything and it should work. it keeps saying that TN=Nothing. anyone see what is the problem?

Hi,

I think it is because you are calling the same function over and over - so the value gets lost. Remember, as you go down one "Node path" you are calling "FindNode" again, and when you find the value that you want and set the return value, it is returning that value back to itself again, and not to the first instance.

Thats the problem - not sure of the solution! Probably a public variable. You could set a public variable with the found value instead of the boolean flag - that way each time you call the "FindNode" function it will just quit out until it gets back to the original calling program or something...?

Hope i was helpful!
DJ

i know that it is the recursin that is screwing it up, but i place breakpoints all over the place and it doesn't call it again after it finds the correct node. I changed the code to use a public variable a few days ago, but this is a bad way to do things as you have to make sure you reset the variable after you are finish with it

You need to store the value that is being returned from the recursive call. Otherwise it gets lost:

Code:

---

       
Dim TN As TreeNode
Dim TMP as TreeNode
For Each TN In TNC
            If Quit = True Then Exit Function
            Debug.WriteLine(TN.Text)
            If TN.Text = Text Then
                FindNode = TN
                Quit = True
                Exit Function
            End If
           
        TMP= FindNode(TN.Nodes, Text)
        'Then check if it is nothing, if it is not nothing, then return it in FindNode
        Next

---

Your function never returns anything, there is no returns in it. It sets the FindNode value, which is basically the samething, but it only does it on the first pass not the recursive ones.
Try this: (I changed it if you were already here)

VB Code:

Public Function FindNode(ByVal nds As TreeNodeCollection, ByVal text As String) As TreeNode
        Dim nd As TreeNode
        For Each nd In nds
            'search current node
            If nd.Text = text Then Return nd
 
            'search child nodes
            Dim subnode As TreeNode = FindNode(nd.Nodes, text)
            'if found then return otherwise keep looking
            If Not subnode Is Nothing Then Return subnode
        Next
    End Function