title: get child nodes xml attribute value
body: <pre><code>&lt;test&gt;
      &lt;acc id="1"&gt; acc1 &lt;/acc&gt;
      &lt;acc id="2"&gt; acc2 &lt;/acc&gt;
      &lt;acc id="3"&gt; acc3 &lt;/acc&gt;
      &lt;acc id="4"&gt; acc4 &lt;/acc&gt;
  &lt;/test&gt;
  </code></pre>
  
  <p>For example, if I want to take the value of each <code>&lt;acc&gt;</code> element:</p>
  
  <pre><code>var iAccs = xdoc.Descendants("test").Elements("acc").Select(p =&gt; p.Value);
  List&lt;string&gt; myList = new List&lt;string&gt;();
  foreach(string p in iAccs)
  {
      myList.Add(p);
  }
  </code></pre>
  
  <p>But how to substract all the attribute "id" values of each <code>&lt;acc&gt;</code> elements?</p>