Extract a part from a specific string pattern
<p>how can I get the time difference from the string below, I want to get it with (-3.30)</p>

<pre><code>[UTC - 3:30] Newfoundland Standard Time
</code></pre>

<p>and how to get null from the below string</p>

<pre><code>[UTC] Western European Time, Greenwich Mean Time
</code></pre>

<p>and I want to get +3.30 in below string</p>

<pre><code>[UTC + 3:30] Iran Standard Time
</code></pre>
