URI Parser 3.1

// place the following code into your index.php
 
define('SELF', 'index.php');
define('PATH', str_replace(SELF, '', __FILE__));
define('URI', str_replace(SELF, '', $_SERVER['SCRIPT_NAME']));
 
function seg($n)
{
  if( $n < 1 ) return false;  // prevent starting from 0
  // prep working vars
  $base_uri = explode('/', URI);
  $req_uri  = $_SERVER['REQUEST_URI'];
  // $n = $n--; // doesn't perform correctly
  $n--;
 
  // clean up request uri
  if(! file_exists(PATH.'.htaccess')) $req_uri = preg_replace('/'.SELF.'/', '', $req_uri, 1);
  foreach($base_uri as $base) $req_uri = preg_replace("/{$base}/", '', $req_uri, 1);
 
  // create a clean array to work from
  $req_uri  = array_merge(array(), array_filter(explode('/', $req_uri)));
 
  // determine if seg is set or not
  $seg  = (isset($req_uri[$n])) ? $req_uri[$n] : false;
 
  // filter bad seg
  if( $seg === false  ||  // $seg not set
      $seg[0] == "?"  ||  // $seg is a query string
      $seg[0] == "#"  ||  // $seg is an html anchor
      $seg[0] == "."      // $seg starts with a '.'
  ) return false;
 
  // clean out unwanted crap trailing on the end of the string
  $seg  = reset(explode(".", $seg));  // file extension filter<code>ing
  $seg  = reset(explode("?", $seg));  // query string filtering
  $seg  = reset(explode("#", $seg));  // html anchor filtering
 
  // return a safe string for processing
  return htmlspecialchars($seg, ENT_QUOTES);
}