Response.Clear();
    Response.Buffer = true;
    Response.AddHeader("content-disposition", "attachment;filename=Ope" + "_" + txtope.Text + ".txt");
    Response.Charset = "utf-8";
    Response.ContentType = "application/text";
   gvope.AllowPaging = false;
   gvope.DataBind();



    StringBuilder sb = new StringBuilder();
    /* for (int k = 0; k <gvope.Columns.Count; k++)
     {
         //add separator
         sb.Append(gvope.Columns[k].HeaderText + '-');
         sb.Clear();

     }*/
    //append new line
    sb.Append("rn");
    for (int i = 0; i <gvope.Rows.Count; i++)
    {
        for (int k = 2; k <gvope.Columns.Count; k++)
        {
            //add separator
            sb.Append(gvop.Rows[i].Cells[k].Text.Trim() + '|');

        }

        //append new line
        sb.Append("rn");
    }
    Response.Output.Write(sb.ToString());
    Response.Flush();
    Response.End();