文字格式转换（Text与Html）

    public string writeStr(string oldStr)
    {
        //oldStr=oldStr.Replace("''","'");   
        oldStr = oldStr.Replace("   ", " ");
        oldStr = oldStr.Replace("&lt;", "<");
        oldStr = oldStr.Replace("&gt;", ">");
        oldStr = oldStr.Replace("<br/>", "\n");
        oldStr = oldStr.Replace("&nbsp;&nbsp;&nbsp;", "\t");
        oldStr = oldStr.Replace("&quot;", "\"");
        return oldStr;
    }
    public string readStr(string oldStr)
    {
        //oldStr=oldStr.Replace("'","''");   
        oldStr = oldStr.Replace("&nbsp;", "   ");
        oldStr = oldStr.Replace("<", "&lt;");
        oldStr = oldStr.Replace(">", "&gt;");
        oldStr = oldStr.Replace("\n", "<br/>");
        oldStr = oldStr.Replace("\t", "&nbsp;&nbsp;&nbsp;");
        oldStr = oldStr.Replace("\"", "&quot;");
        return oldStr;
    }

 在提交文章的时候把换行符Convert.ToString((char)13)   +   Convert.ToString((char)10)替换成HTML代码</P>、<BR>什么的