title: PHP Regular Expression will not match accented characters
body: <p>I am trying to build a regular expression, compatible with PHP that will allow accented characters, for example 'ü'.
  From what I understand the \p{L} operator should do this. What I have so far: </p>
  
  <pre><code>/^[a-z0-9\p{L}][a-z0-9_\p{L}]*/i
  </code></pre>
  
  <p>This should allow a string that can start with any a-z, 0-9 and accented characters and can then be followed by any amount of a-z, 0-9 and accented characters and the entire expression is case insensitive. </p>
  
  <p>However in testing, when using characters such as 'ü' anywhere in the string, the validation fails.
  I have made sure the value being passed is encoded with utf8 by using:</p>
  
  <pre><code>utf8_encode($value)
  </code></pre>
  
  <p>However it still fails. 
  Any suggestions?</p>
  
  <p>Thanks in advance</p>
  
  <p>-------------------------Edit-------------------------</p>
  
  <p>After testing on another server, the original pattern also works.</p>
  
  <pre><code>/^[a-z0-9\p{L}][a-z0-9_\p{L}]*/i
  </code></pre>
  
  <p>The issue appears to be with the server set up.
  I will post the solution when found.</p>