title: Learning C when you already know C++?
body: <p>I think I have an advanced knowledge of C++, and I'd like to learn C.</p>
  
  <p>There are a lot of resources to help people going from C to C++, but I've not found anything useful to do the opposite of that. </p>
  
  <p>Specifically:</p>
  
  <ol>
  <li>Are there widely used general purpose libraries every C programmer should know about (like boost for C++) ?</li>
  <li>What are the most important C idioms (like RAII for C++) ?</li>
  <li>Should I learn C99 and use it, or stick to C89 ?</li>
  <li>Any pitfalls/traps for a C++ developer ?</li>
  <li>Anything else useful to know ?</li>
  </ol>