Exproting Data From GridView To Excel File...?

using System;
using System.Collections;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;
using System.IO;

public partial class DatagridToExcel : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {

    }
    protected void btnExport_Click(object sender, EventArgs e)
    {
        ExportToExcel("report.xls", GridView1);
    }

    private void ExportToExcel(string strFileName, GridView gv)
    {
        Response.Clear();
        Response.Buffer = true;
        Response.ContentType = "application/vnd.xls";
        Response.AddHeader("content-disposition",
        "attachment;filename=" + strFileName);
        Response.Charset = "";
        this.EnableViewState = false;
        System.IO.StringWriter sw = new StringWriter();
        System.Web.UI.HtmlTextWriter htw = new HtmlTextWriter(sw);
        gv.RenderControl(htw);
        Response.Write(sw.ToString());
        Response.End();
    }
    public override void VerifyRenderingInServerForm(Control control)
    {

    }

}

Here you need to include VerifyRenderingInServerForm() Function also...