title: Qt 5 build error: extra characters after test expression
body: <p>I am trying to learn Qt 5.3, and this is my first program (hello world).  When I try to build, it displays this error:</p>
  
  <blockquote>
    <p>extra characters after test expression.</p>
  </blockquote>
  
  <p>I cannot understand at all why this error comes up. I just took some simple code from the Internet to check whether I have installed Qt properly or not.
  Here is the code:</p>
  
  <pre><code>#include &lt;QApplication&gt;
  #include &lt;QPushButton&gt;
  int main(int argc, char **argv)
  {
      QApplication app (argc, argv);
      QPushButton button ("Hello world !");
      button.show();
      return app.exec();
  }
  </code></pre>
  
  <p>The error is displayed in lines 3, 5, 6, 8.
  I am completely new to Qt, so please give a simple explanation.</p>