title: PHP preg_replace on SEO URL not giving expected results
body: <p>So, I have this method:</p>
  
  <pre><code>$seo_special = array("ä", "õ", "ö", "ü", "Ä", "Õ", "Ö", "Ü");
  $seo_special_replace = array("a", "o", "o", "u", "a", "o", "o", "u");
  $seo_tag_a2b = str_replace($seo_special, $seo_special_replace, $row-&gt;name);
  $seo_tag_a2b = preg_replace('/[^a-z0-9-]/i', '', strtolower(str_replace(' ', '-', trim($seo_tag_a2b))));
  </code></pre>
  
  <p>And I expect it to replace special characters to normal ones, but somehow, it skips those characters and the result for <strong>Põrandalaud / Liistparkett</strong> is <strong>prandalaud--liistparkett</strong> when it should be <strong>porandalaud--liistparkett</strong> and I have no idea what I'm doing wrong. Any help would be appreciated. </p>