What is the simplest way to test for a null value in C#
<p>I have a string named ds and need to test only if it <strong>is null or not</strong>. Can I just do the following?</p>

<pre><code>if (ds) { }
</code></pre>

<p>It passes a syntax check so I am wondering what conditions this would test as true.</p>

<p>what does the above code do?</p>
