>Hi Cetin,
>
>thanks for your answer.
>
>

>>   private void WriteDataSetToXMLFile(DataSet ds, string filename)
>>   {
>>	if (ds == null) { return; }
>>	XmlTextWriter xmlWr = new XmlTextWriter(filename, Encoding.UTF8);
>>	xmlWr.Formatting = Formatting.Indented;
>>	XmlSerializer xs = new XmlSerializer(typeof(DataSet));
>>	xs.Serialize(xmlWr, ds);
>>	xmlWr.Close();
>>   }
>

>
>This method writes to a file.
>How can I change it to return the XML string as a return value of the method?

You could use a memorystream:

MemoryStream ms = new MemoryStream();
XmlTextWriter xmlWr = new XmlTextWriter(ms, Encoding.UTF8);

Cetin