title: Allow a-z, A-Z, 0-9, space and -. preg_match
body: <p>How can I allow a-z, A-Z, 0-9, - and space with preg_match.</p>
  
  <p>I currently have the following:</p>
  
  <p><code>if (!preg_match("/^[_a-zA-Z0-9]+$/", $name))</code></p>
  
  <p>Also a side-question, does any of you know a good guide to learn preg_match.</p>