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Exiting from a Recursive Sub Procedure without finishing all iteration

 
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Exiting from a Recursive Sub Procedure without finishing all iteration
dranfu
2 Jan, 2009 - 07:36 PM
Post #1

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Posts: 14
So, I've been applying some recursive techniques to the second version of my app. This recursive procedure simply iterates through all nodes in a tree view and tests whether the text in the "department text box" matches the text name of a particular node. If there is a match, then the user's name, stored in the "name" variable, is added as a node to the node that has the same name as the department text box text.

CODE


CallTestForMatch(TreeView1)

Private Sub TestForMatch(ByVal n As TreeNode)

      Dim aNode As TreeNode
      Dim building1 As String = CStr(building_ComboBox.SelectedItem)
      Dim department1 As String = CStr(department_ComboBox.SelectedItem)
      Dim name As String = ((last_name_TextBox.Text) & ", " & (first_name_TextBox.Text))
      If n.Text = department1 Then
         n.Nodes.Add(name)
         Exit Sub
      End If

      For Each aNode In n.Nodes
         TestForMatch(aNode)
      Next


   End Sub
   Private Sub CallTestForMatch(ByVal aTreeView As TreeView)
      Dim node As TreeNode
      For Each node In aTreeView.Nodes
         TestForMatch(node)
      Next
   End Sub



The only problem is, when a match is found, and the name variable is added to the TreeView as a new node, I want to Exit out of the recursive procedure with the Exit Sub statement. Unfortunately, it doesn't happen. Even when a match is found, the program keeps iterating through every single node until all nodes have been examined. Is there another Keyword I can use to exit the recursive procedure? Do I need to create another procedure to get out of the recursive one?

I'm lost right now.

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Core
RE: Exiting From A Recursive Sub Procedure Without Finishing All Iteration
2 Jan, 2009 - 08:03 PM
Post #2

using DIC.Mod.Core;
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You can add a boolean variable to your code, for example isFound. Declare it right after Public Class FormName and initialize it as False:

CODE

Private isFound As Boolean = False


So, in the TestForMatch method, the verification statement would look like this:

CODE

If n.Text = department1 Then
         n.Nodes.Add(name)
         isFound = True
End If


Then, for the CallTestForMatch method you should use this code:

CODE

      Dim node As TreeNode
      For Each node In aTreeView.Nodes
         TestForMatch(node)
         If isFound = True
             Exit Sub
         End If
      Next


This post has been edited by Core: 2 Jan, 2009 - 08:03 PM
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dranfu
RE: Exiting From A Recursive Sub Procedure Without Finishing All Iteration
2 Jan, 2009 - 08:33 PM
Post #3

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Ok, I will try that, and thanks! But why does it matter if I add the Boolean variable in the calling procedure, versus from the recursive TestForMatch method. Should not "Exit Sub" take me out of the Recursive TestForMatch Methods all together?
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Core
RE: Exiting From A Recursive Sub Procedure Without Finishing All Iteration
2 Jan, 2009 - 08:41 PM
Post #4

using DIC.Mod.Core;
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QUOTE

Should not "Exit Sub" take me out of the Recursive TestForMatch Methods all together?


It just exits the procedure in which it appears. The boolean value in this case will show the program that the needed value has already been found, so if it gets the True value, it will force the For loop to stop.
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dranfu
RE: Exiting From A Recursive Sub Procedure Without Finishing All Iteration
2 Jan, 2009 - 11:32 PM
Post #5

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It didn't work. The method still iterates through every node of the tree, even with the boolean variable.

CODE


CallTestForMatch(TreeView1)


   End Sub ' e-inventory Save Button Click

   Private Sub TestForMatch(ByVal n As TreeNode)

      Dim aNode As TreeNode
      Dim building1 As String = CStr(building_ComboBox.SelectedItem)
      Dim department1 As String = CStr(department_ComboBox.SelectedItem)
      Dim name As String = ((last_name_TextBox.Text) & ", " & (first_name_TextBox.Text))
      If n.Text = department1 Then
         n.Nodes.Add(name)
         IsFound = True
         Exit Sub
      End If

      For Each aNode In n.Nodes
         TestForMatch(aNode)
      Next


   End Sub
   Private Sub CallTestForMatch(ByVal aTreeView As TreeView)
      Dim node As TreeNode
      For Each node In aTreeView.Nodes
         TestForMatch(node)
         If IsFound = True Then
            Exit Sub
         End If

      Next
   End Sub

End Class
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dranfu
RE: Exiting From A Recursive Sub Procedure Without Finishing All Iteration
3 Jan, 2009 - 09:53 AM
Post #6

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Joined: 24 Nov, 2008
Posts: 14
Ok, I got it to work by including the If...Then boolean verification in both of the CallTestForMatch methond and the TestForMatch methond. An example of the working code:

CODE


   Private Sub TestForMatch(ByVal n As TreeNode)

      Dim aNode As TreeNode
      Dim building1 As String = CStr(building_ComboBox.SelectedItem)
      Dim department1 As String = CStr(department_ComboBox.SelectedItem)
      Dim name As String = ((last_name_TextBox.Text) & ", " & (first_name_TextBox.Text))
      If (n.Text = department1) OrElse (n.Text = building1) Then
         n.Nodes.Add(name)
         IsFound = True
         Exit Sub
      End If

      For Each aNode In n.Nodes
         If IsFound = True Then
            Exit Sub
         End If
         TestForMatch(aNode)
      Next


   End Sub
   Private Sub CallTestForMatch(ByVal aTreeView As TreeView)
      Dim node As TreeNode
      For Each node In aTreeView.Nodes
         TestForMatch(node)
         If IsFound = True Then
            Exit Sub
         End If

      Next
   End Sub

End Class



The If...Then needed to be included at both points where it was testing any nodes smile.gif
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