title: PHP considers null is equal to zero
body: <p>In PHP, <code>($myvariable==0)</code>
  When $myvariable is zero, the value of the expression is true; when $myvariable is null, the value of this expression is also true. How can I exclude the second case? I mean I want the expression to be true only when $myvariable is zero. Of course I can write</p>
  <pre><code>($myvariable != null &amp;&amp; $myvariable == 0)
  </code></pre>
  <p>But is there other elegant way to do this?</p>