title: Why php does not complain when referencing a non existing variable?
body: <p>I was wondering why php does not complain when we reference a non existing variable (being it a plain variable or array), is this just the way it is, or there is something else I am missing?
  For example this code</p>
  
  <pre><code>&lt;?php
  $t = &amp;$r["er"];
  var_dump($r);
  ?&gt;
  </code></pre>
  
  <p>throws no warning about a non existing variable.</p>
  
  <p>Besides that the <code>var_dump</code> show this:</p>
  
  <pre><code>array(1) { ["er"]=&gt; &amp;NULL }
  </code></pre>
  
  <p>that <code>&amp;NULL</code> is something I didn't really expected, I thought I would get a plain <code>NULL</code>.</p>
  
  <p>Thanks in advance! </p>