title: PHP regex performance
body: <p>I have to take out some data from strings. Unfortunately data has realy unfriendly format. I had to create about 15 regural expressions placed in separate preg_replace. It's worth to say that they have many OR (|) within itself. My question is what should I do finally: combine all expressions into one and separate them using | or leave them as is - in individual preg_replace?</p>
  
  <p>Is it very bad practice to create other expressions to keep clarity? I think maybe I could combine some expressions into the one but they become very complicated and not understanding.</p>
  
  <p>For example I have:</p>
  
  <pre><code>$itemFullName = preg_replace("@^\b(([a-zA-Z]{1,3})?[0-9]{1,2}(\.|\-|X)[0-9]{1,2}(\s|\.|\-)?(X|x)?\s?[0-9]{1,3}\.?(([0-9]{1,3})?(X[0-9]{1,3})|(\s[0-9]\/[0-9]|\/[0-9]{1,3}))?(\s\#[0-9]{1,3}\/[0-9]{1,3})?)\s@", ' ', $itemFullName, -1, $sum);
  </code></pre>