<?php
 $transport = array('foot', 'bike', 'car', 'plane');
 $mode = current($transport); //$mode = 'foot';
 $mode = next($transport);   // $mode ='bike';
 $mode = current($transport); //$mode = 'bike';
 $mode = prev($transport);   // $mode ='foot';
 $mode = end($transport);    // $mode ='plane';
 $mode = current($transport); //$mode = 'plane';
 ?>

<?php
 $transport = array('foot', 'bike', 'car', 'plane');
 $mode = current($transport); //$mode = 'foot';
 $mode = next($transport);   // $mode ='bike';
 $mode = next($transport);   // $mode ='car';
 $mode = prev($transport);   // $mode ='bike';
 $mode = end($transport);    // $mode ='plane';
 ?>