title: php regular expression backslash dash
body: <p>I'm new in PHP and I'm trying to accommodate php regular expression</p>
  
  <p>from w3schools this regular expression </p>
  
  <pre><code>"/([\w\-]+\@[\w\-]+\.[\w\-]+)/"
  </code></pre>
  
  <p>represents the e-mail regular expression, but I'm wondering what this class definition means <code>"[\w\-]"</code>, <code>\w</code> any word character <strong>but what about <code>"\-"</code>?</strong></p>
  
  <p>(Edited)</p>