title: How to convert anonymous list to string.?
body: <pre><code>XDocument doc = XDocument.Load(reader);
  var IDList = from listings in doc.Root.Elements("SearchData")
               select (string)listings.Attribute("ListingID");
  string list = string.Join(",",IDList);
  </code></pre>
  
  <p>In above case I trying to convert <code>var IDList</code> to string list separated by comma but it error as <code>string.Join(",",IDList)</code> has some invalid argument.</p>
  
  <p>How to do that conversion?</p>