title: Subtraction in regex doesn't get results
body: <p>From a range of <em>aaaa,aaab,....zzzz</em> I'm trying to select using the php function preg_match. The regex are: <code>[b-df-hj-np-tv-z]</code>, <code>[a-z-[aeiuo]]</code> from witch I get:</p>
  
  <p><code>preg_match('/[a-z-[aeiuo]]/',$line)</code> result: Nothing</p>
  
  <p><code>preg_match('/[b-df-hj-np-tv-z]/',$line)</code> result: <code>aaab,aaac,aaad,aaaf,aaag....</code></p>
  
  <p>These are suppose to get the same; any string where there is at least one consonant.</p>
  
  <p>Why doesn't the first one get anything?. Thanks</p>
  
  <p>EDIT: My only main doubt is why <code>[a-z-[aeiuo]]</code> doesn't do the same thing as <code>[b-df-hj-np-tv-z]</code> that's all. I'm trying to learn, excuse me for the confusion.</p>