//读
StringReader reader = new StringReader(s);ds.ReadXml(reader);//写
StringBuilder sb = new StringBuilder();StringWriter writer = new StringWriter(sb);ds.WriteXml(writer);
StringReader reader = new StringReader(s);ds.ReadXml(reader);//写
StringBuilder sb = new StringBuilder();StringWriter writer = new StringWriter(sb);ds.WriteXml(writer);
string str = ds.GetXml();