title: regex unable to allow apostrophe
body: <p>I am experiencing a strange problem with a regular expression I have already used before.
  The goal is to allow the user to enter his name, with letters, hyphen, and apostrophes if needed in a php form.
  My regex is:</p>
  
  <pre><code> "/^[\w\s'àáâãäåçèéêëìíîïðòóôõöùúûüýÿ-]+$/i"
  </code></pre>
  
  <p>But... everything is allowed but the apostrophe. Escaping it will not change. Why?</p>