title: Arguments of Boost's TCP basic_resolver_query constructor
body: <p>I'm having some trouble when putting a very simple c++ program to listen to a given port. Mainly, I have problems when creating a basic_resolver_query. If I do it like this:</p>
  
  <pre><code>boost::asio::ip::tcp::resolver::query query( "0.0.0.0", "5938" );
  </code></pre>
  
  <p>i works flawlessly. But obviously I don't want to hardcode the port, so I've been trying to read it from a file an passing it there: it isn't working. </p>
  
  <p>If I try to pass it directly as <code>std::string</code>, it doesn't work, with I guess was to be expected. But I've tried passing <code>m_listenPort.c_string()</code> and it doesn't do it. </p>
  
  <p>I've been trying to look in the documentation, and in examples, but I can find nothing. How do I have to do it?</p>