title: what's the meaning of "|=" in PHP
body: <p>I'm reading other's php code, and there's one line writes:</p>
  
  <pre><code>    if ($isprivate)
    {
      $status |= STATUS_PRIVATE;
    }
  </code></pre>
  
  <p>I have no idea what does "|=" mean?
  Can anyone help on it?</p>