<p>I'm using this simple regular expression to validate a hex string:</p>

<pre><code>^[A-Fa-f0-9]{16}$
</code></pre>

<p>As you can see, I'm using a quantifier to validate that the string is 16 characters long. I was wondering if I can use another quantifier in the same regex to validate the string length to be either 16 or 18 (not 17).</p>

```
```
^(?:[A-Fa-f0-9]{16}|[A-Fa-f0-9]{18})$
```
```