C#

if(row.Cells["colStudentId"].Value != DBNull.Value){
...
}

private void button1_Click(object sender, EventArgs e)
{
   // show all the nodes expanded
   treeView1.ExpandAll();

   RecursiveParseTree(treeView1.Nodes, 0);
}

private void RecursiveParseTree(TreeNodeCollection nodeCollection, int level)
{
    foreach (TreeNode theNode in nodeCollection)
    {
        Console.WriteLine
        (
            "Node Name: = {0}, 
            Node Level = {1}, 
            Node Checked = {2}", 
            theNode.Text, 
            level, 
            theNode.Checked
        );

        if (theNode.Nodes.Count > 0)
        {
            RecursiveParseTree(theNode.Nodes, level++);
        }
    }
}

    private void Load_treeView_NodeMouseClick(object sender, TreeNodeMouseClickEventArgs e)
       {    // For Select all to sub tree
           TreeNode parent_node = e.Node;
           bool is_checked = parent_node.Checked;

           for (int i = 0; i <= e.Node.Nodes.Count - 1; i++)
           {
               //MessageBox.Show(i.ToString());
               SetSubtreeChecked(parent_node.Nodes[i], is_checked);

           }

           bool blnUncheck = false;

           //---------------------------------------------------
           //Check to see if a parent node exists.



           if ((e.Node.Parent != null))
           {
               //Loop through the child nodes.
               foreach (TreeNode child in e.Node.Parent.Nodes)
               {
                   //Check to see if the current node is unchecked.
                   if (child.Checked == true)
                   {
                      //Set the variable.
                       blnUncheck = true;
                   }
               }
               //Check the variable.
               if (blnUncheck == false)
               {
                   //Check the parent node.
                   e.Node.Parent.Checked = false;
               }
               else
               {
                   //Uncheck the parent node.
                   e.Node.Parent.Checked = true;
               }
           }
     }

private void SetSubtreeChecked(TreeNode parent_node, bool is_checked)
       {
           // Set the parent's Checked value.
           parent_node.Checked = is_checked;
           // Set the child nodes' Checked values.
           for (int i = 0; i <= parent_node.Nodes.Count - 1; i++)
           {
               SetSubtreeChecked(parent_node.Nodes[i], is_checked);
           }
       }

JANARDHAN GURRAM wrote:

can i call this RecursiveParseTree() in any of the events of the treeview1 or 2 so that i need not click the button??

TreeNode targetNode = ????;
//
if(targetNode.Nodes.Count > 0)
{
  // call the recursive parser
  RecursiveParseTree(targetNode.Nodes,0);
}
else
{
  // consider how you want to respond to essentially a no-op
}

 private void Load_treeView_AfterCheck(object sender, TreeViewEventArgs e)
        {
               RecursiveParseTree(e.Node, 0);              
         }
 private void RecursiveParseTree(TreeNode thenode, int level)
        {
            // for adding the checked nodes and its child nodes(if they are checked) from the _dataArray list
                if(thenode.Checked==true)
                {
                foreach(TreeNode childNode in thenode.Nodes)
                    if (childNode.Checked == true)
                   {
                       _dataArray.Add(new string[] { thenode.Text, childNode.Text });
                    }
                }

            // for deleting the unchecked nodes and its child nodes from the _dataArray list
                if (thenode.Checked == false)
                {
                    foreach (TreeNode childNode in thenode.Nodes)
                    {
                        List<string> Key = new List<string> { thenode.Text, childNode.Text };
                        _dataArray.RemoveAll(item => Enumerable.SequenceEqual(item, Key));
                    }

                }

       }
<div class="signature">JANARDHAN</div>