Exporting to excel with formating and preserving starting(Leading) zeros

public static void ExportToExcel(DataTable dt, string fileNameWithoutExtension)
{
    try
    {
 if (dt.Rows.Count > 0)
 {
     //Note: For simple Export uncomment the below code and use it.
     //////System.IO.StringWriter tw = new System.IO.StringWriter();
     //////System.Web.UI.HtmlTextWriter hw = new System.Web.UI.HtmlTextWriter(tw);
     //////DataGrid dgGrid = new DataGrid();
     //////dgGrid.DataSource = dt;
     //////dgGrid.DataBind();
     ////////Get the HTML for the control.
     //////dgGrid.RenderControl(hw);
     ////////Write the HTML back to the browser.
     ////////Response.ContentType = application/vnd.ms-excel;
     //////HttpContext.Current.Response.ContentType = "application/vnd.ms-excel";
     //////HttpContext.Current.Response.AppendHeader("Content-Disposition", "attachment; filename=" + fileNameWithoutExtension.Trim() + ".xls" + "");
     ////////this.EnableViewState = false;
     //////HttpContext.Current.Response.Write(tw.ToString());
     //////HttpContext.Current.Response.End();

     //Note : For Exporting to excel with formating and preserving starting(Leading) zeros use below code.
     String style = "<style>.text{mso-number-format:\\@;}</style>";
     HttpContext.Current.Response.Clear();
     HttpContext.Current.Response.Buffer = true;
     HttpContext.Current.Response.AddHeader("Content-Disposition", "attachment; filename=" + fileNameWithoutExtension.Trim() + ".xls" + "");
     HttpContext.Current.Response.ContentType = "application/excel";
     StringWriter sw = new StringWriter();
     System.IO.StringWriter ioSw = new System.IO.StringWriter();
     System.Web.UI.HtmlTextWriter htw = new System.Web.UI.HtmlTextWriter(ioSw);
     GridView GridView1 = new GridView();
     GridView1.AllowPaging = false;
     GridView1.DataSource = dt;
     GridView1.DataBind();
    
     //Change the Header Row
     GridView1.HeaderRow.Style.Add("background-color", "#cc0000");
    
     //Apply style to Individual Cells    
     GridView1.HeaderRow.Cells[0].Style.Add("background-color", "green");
     for (int i = 0; i < GridView1.Rows.Count; i++)
     {
  GridViewRow row = GridView1.Rows[i];
  //Apply text style to each Row        
  row.Attributes.Add("class", "textmode");
  //Apply style to Individual Cells of Alternating Row        
  if (i % 2 != 0)        
  {
   row.Cells[1].Attributes.Add("class", "text");//Format individual Column as text to preserve leading zeros
   row.Cells[2].Style.Add("background-color", "#C2D69B");
  }
     }
     //Remove Controls    
     this.RemoveControls(GridView1);
     GridView1.RenderControl(htw);
     HttpContext.Current.Response.Output.Write(style + ioSw.ToString());
     HttpContext.Current.Response.Flush();
     HttpContext.Current.Response.End();
 }
 else
 {
     throw new Exception("No records to export");
 }
    }
    catch (Exception ex)
    {
 throw ex;
    }
}
private void RemoveControls(Control grid)
{
    Literal literal = new Literal();
    for (int i = 0; i < grid.Controls.Count; i++)
    {
 if (grid.Controls[i] is LinkButton)
 {
     literal.Text = (grid.Controls[i] as LinkButton).Text;
     grid.Controls.Remove(grid.Controls[i]);
     grid.Controls.AddAt(i, literal);
 }
 else if (grid.Controls[i] is DropDownList)
 {
     literal.Text = (grid.Controls[i] as DropDownList).SelectedItem.Text;
     grid.Controls.Remove(grid.Controls[i]);
     grid.Controls.AddAt(i, literal);
 }
 else if (grid.Controls[i] is CheckBox)
 {
     literal.Text = (grid.Controls[i] as CheckBox).Checked ? "True" : "False";
     grid.Controls.Remove(grid.Controls[i]);
     grid.Controls.AddAt(i, literal);
 }
 else if (grid.Controls[i] is HyperLink)
 {
     literal.Text = (grid.Controls[i] as HyperLink).Text;
     grid.Controls.Remove(grid.Controls[i]);
     grid.Controls.AddAt(i, literal);
 }
 else if (grid.Controls[i] is Button)
 {
     literal.Text = (grid.Controls[i] as Button).Text;
     grid.Controls.Remove(grid.Controls[i]);
     grid.Controls.AddAt(i, literal);
 }
 if (grid.Controls[i].HasControls())
 {
     RemoveControls(grid.Controls[i]);
 }
    }
}