title: Strange Compiler error with header file on Arduino
body: <p>I starting off a project and starting build some of its structure. I am basing each sensor with a header file and c++ source file under the Arduino's Sensor library in a folder named "Sensors". The file it is complaining about is rather small and uninteresting since it has just been created.</p>
  
  <p><strong>Error:</strong></p>
  
  <pre><code>In file included from /Applications/Arduino.app/Contents/Resources/Java/libraries/PID/../Sensors/Sensors.h:6,
               from Aircraft.h:5,
               from Aircraft.cpp:1:
  /Applications/Arduino.app/Contents/Resources/Java/libraries/PID/../Sensors/Compass.h:14: error: multiple types in one declaration
  </code></pre>
  
  <p><strong>Compass.h</strong></p>
  
  <pre><code>#pragma once
  
  class Compass
  {
  private:
      double x,y,z;
  
  public:
      void refresh();
  
      double getX();
      double getY();
      double getZ();
  };
  </code></pre>
  
  <p>It complains about <code>multiple types in one declaration</code>. But the file seems to be fine. Is there something I am missing? Something I overlooked?</p>