title: Double forward slash in regular expression
body: <p>I want to use preg_split to split a string on double forward slash (//) and question mark (?). I can use a single forward slash like this:</p>
  
  <pre><code>preg_split('[\/]', $string);
  </code></pre>
  
  <p>But </p>
  
  <pre><code>preg_split('[\//]', $string);
  or
  preg_split('[\/\/]', $string);
  </code></pre>
  
  <p>do not work.</p>
  
  <p>How do you work with a double forward slash in an expression?</p>