Asp.net Gridviewer Karakter Sınırlandırma ?

TableCell cell = new TableCell();
        string s = HttpUtility.HtmlDecode(cell.Text);
        if (cell.Text.Length > 25)
            cell.Text = s.Substring(0, 25) + "....";
        cell.ToolTip = s;

protected void Page_Load(object sender, EventArgs e)
        {
            if (!IsPostBack)
                griddoldur();
         }
 
        public void griddoldur()
        {
            SqlConnection baglanti = klas.baglan();
            DataSet dts = new DataSet();
            SqlCommand cmd = new SqlCommand("Select * from mesaj", baglanti);
            SqlDataAdapter da = new SqlDataAdapter(cmd);
            da.Fill(dts);
            GridView1.DataSource = dts;
            GridView1.DataBind();
                   }
        protected void karaktersinirla(object sender, GridViewRowEventArgs e)
        {
            int i = 0;
            
            if (e.Row.RowType == DataControlRowType.DataRow)
            {
                foreach (TableCell cell in e.Row.Cells)
                {
                    i++;
                    string s = HttpUtility.HtmlDecode(cell.Text);
                    if (cell.Text.Length > 25 )
                        cell.Text = s.Substring(0, 25) + "....";
                    cell.ToolTip = s;
                }
            }
        }

.css{
overflow: hidden;
text-overflow: ellipsis;
white-space: nowrap;
}

protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
{
    if (e.Row.RowType == DataControlRowType.DataRow)
    {
        foreach (TableCell cell in e.Row.Cells)
        {
            
        }
    }
}