Visual Basic

Private Sub cmdCreateXLTemplate_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdCreateXLTemplate.Click
        Dim ColHeadings() As String = {"warehouse", "product", "alpha"} 
       
        Dim xlApp As New Excel.Application
        Dim xlBook As Excel.Workbook
        Dim Row As Integer = 1
        Dim Col As Integer

        xlBook = xlApp.Workbooks.Add
        xlBook.Sheets(2).Name = "ErrorData"
        'Column Headings
        For Col = 1 To ColHeadings.GetUpperBound(0)
            xlBook.Sheets(1).cells(2, Col) = ColHeadings(Col - 1)
        Next

        'Actual Data
        For j As Integer = 0 To Me.dgExcelData.RowCount - 1
            xlBook.Sheets(1).cells(j+1, 1) = Me.dgExcelData.Item(0, j).ToString
        Next
        'Saving The Excel File
        Dim Filename As String
        Filename = Application.StartupPath & "\Import.xls"
        Dim i As Integer = 1
        Do While IO.File.Exists(Filename)
            Filename = "C:\Import" & i & ".xls"
        Loop
        Dim Save As New SaveFileDialog
        Save.FileName = Filename
        Dim Result As DialogResult
        Result = Save.ShowDialog
        If Result = Windows.Forms.DialogResult.OK Then
            xlBook.SaveAs(Filename)
        End If

        xlBook.Close()
        xlBook = Nothing
        xlApp.Quit()
        xlApp = Nothing
        GC.Collect()
    End Sub

treeview.FindNode("NewNode/NewNode").Expand()'node path
treeview.Nodes.Item(i).Expand()'node index
treeview.SelectedNode.Expand()