title: c++ and boost program_options error: 'desc' does not name a type
body: <p>I'm trying to follow <a href="http://www.boost.org/doc/libs/1_55_0/doc/html/program_options/tutorial.html" rel="nofollow">this tutorial on boost program_options</a>, but I'm getting this error:</p>
  
  <p>error: 'desc' does not name a type.</p>
  
  <p>Here is the source code I have:</p>
  
  <pre><code>#include &lt;boost/program_options.hpp&gt;
  
  using namespace std;
  
  namespace po = boost::program_options;
  
  po::options_description desc("Allowed options");
  desc.add_options()
      ("help", "produce help message")
      ("compression", po::value&lt;int&gt;(), "set compression level")
  ;
  
  int main()
  {
      return 0;
  }
  </code></pre>
  
  <p>the error is on the line starting with 'desc.add_options', not the line where I construct it.</p>
  
  <p>/usr/local/boost is my BOOST_ROOT, and I have it added to my code blocks compiler settings.  The compiler arg is -I/usr/local/boost</p>
  
  <p>Why is this not working?</p>