Export to excel from gridview C# (excel template)

Private Void ExportExcelFile()
{
       DataTable dt=new DataTable();
       dt=(DataTable)ViewState["dtData"];
       

        GridView gvExp = New GridView();
        gvExp.AutoGenerateColumns = False;

        int counter = 0;
        foreach(DataColumn col In GriedView1.Columns)
        {
            BoundField bf = New BoundField();
            bf.DataField = col.ColumnName;
            bf.HeaderText = col.ColumnName;
            gvExp.Columns.Add(bf);
            counter += 1;
        }

        gvExp.DataSource = dt;
        gvExp.DataBind();

        String FileName = ""
        FileName = "YourFileName.xls";

        Response.Clear();
        Response.AddHeader("content-disposition", "attachment;filename=" & FileName);
        Response.ContentType = "application/ms-excel";
        Response.ContentEncoding = System.Text.Encoding.Unicode;
        Response.Charset = "";
        Response.BinaryWrite(System.Text.Encoding.Unicode.GetPreamble());

        
        System.IO.StringWriter tw = New System.IO.StringWriter();
        System.Web.UI.HtmlTextWriter hw = New System.Web.UI.HtmlTextWriter(tw);

        gvExp.RenderControl(hw);
        Response.Write(tw.ToString());
        Response.End();
}


Hope it helps you.