Export GridView in ASP.NET to excel

protected void btnExport_Click(object sender, EventArgs e)
{
Response.Clear();
Response.AddHeader("content-disposition", "attachment;filename=ExportFile.xls");
Response.Charset = "";
Response.ContentType = "application/vnd.xls";
System.IO.StringWriter stringWrite = new System.IO.StringWriter();
System.Web.UI.HtmlTextWriter htmlWrite = new HtmlTextWriter(stringWrite);
gvReport.RenderControl(htmlWrite);
Response.Write(stringWrite.ToString());
Response.End();
}
public override void VerifyRenderingInServerForm(Control control)
{
/* Verifies that the control is rendered */
}