搜索后关键字替换颜色

<script language="C#" runat="server">
    string GetTitle(object str)
    {    
        if(str!=null)
        {
            if(str.ToString().Length > 30)
            {
                return str.ToString().Substring(0,30) + "";        
            }        
            return str.ToString();
        }
        else
        {
            return "";
        }
    }    
   string SelectText(object str)
    {            
        if(!stemp.Equals(""))
        {
            if(str!=null)
            {
                return str.ToString().Replace(stemp.ToUpper(),"<font color=#ff3300>"+stemp.ToUpper()+"</font>");
            }
            return "";
        }
        return str.ToString();
    } 
</script>