title: Correct includes to use the new C++ API in opencv 2.3
body: <p>I'm familiar with the old opencv 1, and used its C functions for a long time. However, I have problems with switching to the C++ API of opencv 2.3</p>
  
  <p>I downloaded the latest stable version (2.3.1), but the examples in it use either the old C functions, or include <code>"opencv2/highgui/highgui.hpp"</code>.</p>
  
  <p>The problem is, <strong>the only file in my <code>include/opencv2</code> directory is <code>opencv.hpp</code></strong>. If I include that, there are a lot of paths which are incorrect.
  Inside of <code>opencv.hpp</code> there are such things as:</p>
  
  <pre><code>#include "opencv2/core/core_c.h"
  #include "opencv2/core/core.hpp"
  #include "opencv2/flann/miniflann.hpp"
  #include "opencv2/imgproc/imgproc_c.h"
  </code></pre>
  
  <p>etc.</p>
  
  <p>However, in my opencv directory, the include files are in folders like: </p>
  
  <pre><code>modules/core/include/opencv2/core
  modules/flann/include/opencv2/flann
  modules/imgproc/include/opencv2/imgproc
  </code></pre>
  
  <p>etc. </p>
  
  <p>So, what is the point of that <code>opencv.hpp</code>, if I have to specify the include path manually for every single header? On the opencv site (http://opencv.willowgarage.com) the tutorials are either hopelessly outdated, or they don't address this question at all and jump straight to the algorithms.</p>
  
  <p><strong>Edit:</strong> I'm using Qt, if that matters. I downloaded the source from <a href="http://code.opencv.org/svn/opencv/branches/2.3/" rel="nofollow">http://code.opencv.org/svn/opencv/branches/2.3/</a> and built it successfully.</p>
  
  <p><strong>Edit2:</strong> Yes, it mattered. One of the Qt headers was missing, and so the building process of opencv skipped a few libraries.</p>