ASP.NET

public void ExportToExcel(DataTable dataTable)
{
		string filename = "Report.xls";
		StringWriter tw = new System.IO.StringWriter();
		HtmlTextWriter hw = new System.Web.UI.HtmlTextWriter(tw); 
		DataGrid dgGrid = new DataGrid();
		dgGrid.DataSource = dataTable;
		dgGrid.DataBind();
		dgGrid.RenderControl(hw);
		HttpContext.Current.Response.ContentType = "application/vnd.ms-excel";
		HttpContext.Current.Response.AppendHeader("Content-Disposition", "attachment; filename=" + filename + ""); 
		HttpContext.Current.Response.Write(tw.ToString());
		HttpContext.Current.Response.End();
}