DataGrid Export to excel file

private void ExportGridToExcel(DataGrid grdGridView, string fileName)
{
Response.Clear();
Response.AddHeader("content-disposition", string.Format("attachment;filename={0}.xls", fileName));
Response.Charset = "";
Response.ContentType = "application/vnd.xls";
StringWriter stringWrite = new StringWriter();
HtmlTextWriter htmlWrite = new HtmlTextWriter(stringWrite);
grdGridView.RenderControl(htmlWrite);
Response.Write(stringWrite.ToString());
Response.End();
}