regex

<?php
      // if the $field_url is not present, proceed as normal
      if (empty($field_url)) {
        echo $content;
      // if the $field_url is present, format it as an actual url
      // the problem here is that $content may contain multiple urls, I want to do a regex
      // on only the $detected_field_url, even if the $detected_field_url is found multiple times in $content
      } else {
        $detected_field_url = preg_quote($field_url, '/');

        $formatted_url = '<a href="$detected_field_url">"$detected_field_url"</a>';
        $formatted_url = preg_quote($formatted_url, '/');

        // this is still not echoing anything, i think i am missing something dumb on my part..
        echo preg_replace($detected_field_url, $formatted_url, $content);
      }
?>