docs-desktop/dotnet-desktop-guide/framework/winforms/controls/how-to-iterate-through-all-nodes-of-a-windows-forms-treeview-control.md

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title	ms.date	dev_langs	helpviewer_keywords	ms.assetid
Iterate Through All Nodes of TreeView Control	03/30/2017	csharp vb cpp	examples [Windows Forms], TreeView control TreeView control [Windows Forms], iterating through nodes tree nodes in TreeView control [Windows Forms], iterating through	427f8928-ebcf-4beb-887f-695b905d5134

How to: Iterate Through All Nodes of a Windows Forms TreeView Control

It is sometimes useful to examine every node in a Windows Forms xref:System.Windows.Forms.TreeView control in order to perform some calculation on the node values. This operation can be done using a recursive procedure (recursive method in C# and C++) that iterates through each node in each collection of the tree.

Each xref:System.Windows.Forms.TreeNode object in a tree view has properties that you can use to navigate the tree view: xref:System.Windows.Forms.TreeNode.FirstNode%2A, xref:System.Windows.Forms.TreeNode.LastNode%2A, xref:System.Windows.Forms.TreeNode.NextNode%2A, xref:System.Windows.Forms.TreeNode.PrevNode%2A, and xref:System.Windows.Forms.TreeNode.Parent%2A. The value of the xref:System.Windows.Forms.TreeNode.Parent%2A property is the parent node of the current node. The child nodes of the current node, if there are any, are listed in its xref:System.Windows.Forms.TreeNode.Nodes%2A property. The xref:System.Windows.Forms.TreeView control itself has the xref:System.Windows.Forms.TreeView.TopNode%2A property, which is the root node of the entire tree view.

To iterate through all nodes of the TreeView control

1. Create a recursive procedure (recursive method in C# and C++) that tests each node.

2. Call the procedure.

   The following example shows how to print each xref:System.Windows.Forms.TreeNode object's xref:System.Windows.Forms.TreeNode.Text%2A property:

   Private Sub PrintRecursive(ByVal n As TreeNode)  
      System.Diagnostics.Debug.WriteLine(n.Text)  
      MessageBox.Show(n.Text)  
      Dim aNode As TreeNode  
      For Each aNode In n.Nodes  
         PrintRecursive(aNode)  
      Next  
   End Sub  
   
   ' Call the procedure using the top nodes of the treeview.  
   Private Sub CallRecursive(ByVal aTreeView As TreeView)  
      Dim n As TreeNode  
      For Each n In aTreeView.Nodes  
         PrintRecursive(n)  
      Next  
   End Sub  
   

   private void PrintRecursive(TreeNode treeNode)  
   {  
      // Print the node.  
      System.Diagnostics.Debug.WriteLine(treeNode.Text);  
      MessageBox.Show(treeNode.Text);  
      // Print each node recursively.  
      foreach (TreeNode tn in treeNode.Nodes)  
      {  
         PrintRecursive(tn);  
      }  
   }  
   
   // Call the procedure using the TreeView.  
   private void CallRecursive(TreeView treeView)  
   {  
      // Print each node recursively.  
      TreeNodeCollection nodes = treeView.Nodes;  
      foreach (TreeNode n in nodes)  
      {  
         PrintRecursive(n);  
      }  
   }  
   

   private:  
      void PrintRecursive( TreeNode^ treeNode )  
      {  
         // Print the node.  
         System::Diagnostics::Debug::WriteLine( treeNode->Text );  
         MessageBox::Show( treeNode->Text );  
   
         // Print each node recursively.  
         System::Collections::IEnumerator^ myNodes = (safe_cast<System::Collections::IEnumerable^>(treeNode->Nodes))->GetEnumerator();  
         try  
         {  
            while ( myNodes->MoveNext() )  
            {  
               TreeNode^ tn = safe_cast<TreeNode^>(myNodes->Current);  
               PrintRecursive( tn );  
            }  
         }  
         finally  
         {  
            IDisposable^ disposable = dynamic_cast<System::IDisposable^>(myNodes);  
            if ( disposable != nullptr )  
                     disposable->Dispose();  
         }  
      }  
   
      // Call the procedure using the TreeView.  
      void CallRecursive( TreeView^ treeView )  
      {  
         // Print each node recursively.  
         TreeNodeCollection^ nodes = treeView->Nodes;  
         System::Collections::IEnumerator^ myNodes = (safe_cast<System::Collections::IEnumerable^>(nodes))->GetEnumerator();  
         try  
         {  
            while ( myNodes->MoveNext() )  
            {  
               TreeNode^ n = safe_cast<TreeNode^>(myNodes->Current);  
               PrintRecursive( n );  
            }  
         }  
         finally  
         {  
            IDisposable^ disposable = dynamic_cast<System::IDisposable^>(myNodes);  
            if ( disposable != nullptr )  
                     disposable->Dispose();  
         }  
      }  
   

See also

• TreeView Control
• Recursive Procedures