title: Programming problem that I can't understand ++i behaviour
body: <p>why does</p>
  <pre><code>int a = 0;
  cout&lt;&lt; (++a) + (++a) + (++a) 
  </code></pre>
  <p>show 9 as a result since it should be:
  1 + 2 + 3 that is 6</p>