数据绑定控件，字符串截取问题？

前台：<%#getString((DataBinder.Eval(Container.DataItem,"content")).ToString(),200)%>

后台：

protected string getString(string s, int n)
    {
        if (s.Length == n)
            return s;
        else
            if (s.Length > n)
                return s.Substring(0, n) + "… ";
            else
                if (s == " " || s == null)
                    return " ";
                else
                {
                    string a = s;
                    for (int i = 0; i <= (n - s.Length - 1); i++)
                    {
                        a += "&nbsp;&nbsp; ";
                    }
                    return a;
                }
    }