PHP 数组函数 current()

<?php
   $transport = array('foot', 'bike', 'car', 'plane');
   $mode = current($transport);
   print "$mode <br />";

   $mode = next($transport);  
   print "$mode <br />";

   $mode = current($transport);
   print "$mode <br />";

   $mode = prev($transport);  
   print "$mode <br />";

   $mode = end($transport);
   print "$mode <br />";

   $mode = current($transport);
   print "$mode <br />";
?>