Export GridView to excel

Below code is for GridView

string attachment = “attachment;filename=Contacts.xls”;
Response.ClearContent();
Response.AddHeader(“content-disposition”, attachment);
Response.ContentType = “application/ms-excel”;
StringWriter sw = new StringWriter();
HtmlTextWriter htw = new HtmlTextWriter(sw);
GridView1.RenderControl(htw);
Response.Write(sw.ToString());
Response.End();

Below Code is for DataGrid

Response.ClearContent();
Response.AddHeader(“content-disposition”, “attachment; filename=” + strFileName);
Response.ContentType = “application/excel”;
System.IO.StringWriter sw = new System.IO.StringWriter();
HtmlTextWriter htw = new HtmlTextWriter(sw);
dg.RenderControl(htw);
Response.Write(sw.ToString());
Response.End();