export data to excel from gridview

public void ExportGridToExcel(GridView 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.Flush();
Response.End();
}

public override void VerifyRenderingInServerForm(Control control)
{

}