title: What is the default path for OSX system include files when building a C++ application?
body: <p>I am building a C++ application at the command line (using <code>make</code> with an open-source library (Xerces 2.8)).  One of the files includes an OSX system file,</p>
  
  <pre><code>#include &lt;TextUtils.h&gt;
  </code></pre>
  
  <p>When I type <code>make -n</code> to determine the command used to compile the given file, there is no include path for the system framework files provided.  Therefore, I assume that on OSX the gcc compiler looks in a default location for system include files.</p>
  
  <p>I would like to know what this location is.  When I search for <code>TextUtils.h</code>, I see many versions of the file in different locations, including a few different possible candidates for what might be a default location.</p>
  
  <p>How can I determine the default path the system uses for system include files?</p>