title: Regex: Add space if letter is adjacent to a number
body: <p>I'm using PHP and not really good with regex. I need a preg_replace that can add a space if a letter or number is adjacent.</p>
  
  <p>These are the scenarios:</p>
  
  <pre><code>mystreet12 -&gt; mystreet 12
  mystreet 38B -&gt; mystreet 38 B
  mystreet16c -&gt; mystreet 16 c
  my street8 -&gt; my street 8
  </code></pre>
  
  <p>Thanks.</p>