title: C++11 Regex Capture Groups By Name
body: <p>I am converting my boost-based regular expressions to C++11 regex. I have a capture group called <code>url</code>:</p>
  
  <pre><code>\s*?=\s*?(("(?&lt;url&gt;.*?)")|('?&lt;url&gt;.*?)'))
  </code></pre>
  
  <p>With boost, if you had an <code>smatch</code> you could call <code>match.str("url")</code> to get the capture group by name. With <code>std::smatch</code>, I am only seeing indexed sub-matches.</p>
  
  <p>How can I get access to the url capture using the std::smatch class?</p>