title: Allowing only one alpha character - RegEx
body: <p>I am trying  to only allow one single character suing regex but it seems that it is allowing multiple amounts through.</p>
  
  <p>I have tried this..</p>
  
  <pre><code>$char = trim($_REQUEST['char']);
  
  /* Validate char */
  
  if (preg_match('/[^a-zA-Z]{1}/', $char)) {
      $char = 'a';
  }
  
  echo $char;
  </code></pre>
  
  <p>and this..</p>
  
  <pre><code>$char = trim($_REQUEST['char']);
  
  /* Validate char */
  
  if (!preg_match('/[a-zA-Z]{1}/', $char)) {
      $char = 'a';
  }
  
  echo $char;
  </code></pre>
  
  <p>But neither work. They always output the result even if <code>$_REQUEST['char']</code> is equal to <code>aa</code>.</p>