title: Difference between creating object with () or without
body: <p>i just run into the problem </p>
  
  <pre><code>error: request for member ‘show’ in ‘myWindow’, which is of non-class type ‘MainGUIWindow()’
  </code></pre>
  
  <p>when trying to compile a simple qt-application:</p>
  
  <pre><code>#include &lt;QApplication&gt;
  #include "gui/MainGUIWindow.h"
  
  
  int main( int argc, char** argv )
  {
    QApplication app( argc, argv );
  
  
    MainGUIWindow myWindow();
    myWindow.show();
  
  
    return app.exec();
  }
  </code></pre>
  
  <p>I solved this by replacing </p>
  
  <pre><code>MainGUIWindow myWindow(); 
  </code></pre>
  
  <p>by</p>
  
  <pre><code>MainGUIWindow myWindow;
  </code></pre>
  
  <p>but I don't understand the difference. My question: What is the difference?</p>
  
  <p>Regards,
  Dirk</p>