php代码求分析,该如何处理

<br />echo join(' - ', $_GET), '<br>';  // ①<br />$dict = array(<br />  'area' => array('内地', '港台'),<br />  'type' => array('动作', '爱情'),<br />  'year' => array('2001', '2013'),<br />);<br />foreach($dict as $key=>$item) {<br />  $param = $_GET;                 //②<br />  foreach($item as $v) {<br />    $param[$key] = $v;             //③<br />    $t = http_build_query($param); //④<br />    echo "<a href='/search.php?$t'>$v</a> ";<br />  }<br />  echo '<br>';<br />}