Export to Excel form C# code behind

 1. create a gridview and fetch data into it and then

insert this code to button click 

        string FileName = DateTime.Now.ToString();

        Response.Clear();

        Response.AddHeader("content-disposition", "attachment;filename="+FileName+".xls");

        Response.Charset = "";

        // If you want the option to open the Excel file without saving then

        // comment out the line below

        // Response.Cache.SetCacheability(HttpCacheability.NoCache);

        Response.ContentType = "application/vnd.xls";

        System.IO.StringWriter stringWrite = new System.IO.StringWriter();

        System.Web.UI.HtmlTextWriter htmlWrite = new HtmlTextWriter(stringWrite);

        gvExport.RenderControl(htmlWrite);

        Response.Write(stringWrite.ToString());

        Response.End();

in above code file name is given datetime.