title: What is $x+++$X++ in PHP? Unusual use of increment
body: <p>Few days ago i was on interview and I had one task to do with, to me, unknown use of increment. It goes exactly like this:</p>
  
  <pre><code>echo $x+++$x++;
  </code></pre>
  
  <p>I've never seen something like this before, I'm trying to figure out what it does and I'm clueless. To check it i wrote such code sample:</p>
  
  <pre><code>&lt;?php
  $x = 7;
  
  echo $x. "&lt;br&gt;";
  echo $x+++$x++;
  ?&gt;
  </code></pre>
  
  <p>First line prints out what it is supposed to print out: <code>7</code>.<br>
  But second line prints out <code>15</code>. Why? How does this thing work? What does it mean?</p>
  
  <p>Is it just me or is it similar thing as variable variable which is funny task from interviewers but is not useful in reality?</p>