title: preg_replace all but numbers, letters, periods, and slash?
body: <p>I have a regular expression that strips everything but letters. numbers, and periods.  How do I also add foreslashes to it?</p>
  
  <pre><code>$targetFile = preg_replace('/[^A-Za-z0-9-.]/', '', $targetFileDirty);
  </code></pre>