php教程--案例19（保存浏览历史）

<?php
//case 19 保存浏览历史
//虚拟新闻数组
$all_data = array(
    1=>array('学习php','月薪万元不是梦','......'),
    2=>array('学习java','日薪万元不是梦','......'),
    3=>array('我是程序员','成为高富帅，迎娶白富美','......'),
    4=>array('学习编程的终极奥义','秃头秃头再秃头','.....')
);
//获取新闻id
$id = isset($_GET['id'])?intval($_GET['id']):1;
//限定边界
$id_prev = $id - 1;
$id_next = $id + 1;
if($id < 1) $id = 1;
if($id > 4) $id = 4;
if($id_prev < 1) $id_prev = 1;
if($id_next > 4) $id_next = 4;
//有cookie
if(isset($_COOKIE['history']))
{
    $cookie_arr = explode(',',$_COOKIE['history'],4);
    foreach ($cookie_arr as $k=>$v)
    {
        $cookie_arr[$k] = intval($cookie_arr[$k]);
        if($v == $id) unset($cookie_arr[$k]);
    }
    if(count($cookie_arr) > 3) array_shift($cookie_arr);
    $cookie_arr[] = $id;
    setcookie('history',implode(',',$cookie_arr));
}
//保存cookie
else
{
    $cookie_arr = array($id);
    setcookie('history',$id);
}
//清除
if(isset($_GET['action']))
{
    if($_GET['action'] == 'clear')
    {
        $cookie_arr = array();
        setcookie('history','',time()-1);
    }
}
//显示
$data = $all_data[$id];
$data_history = array();
foreach ($cookie_arr as $v)
{
    if(isset($all_data[$v]))
    {
        $data_history[$v] = $all_data[$v][0];
    }
}

?>

<div class="content">
    <?php echo $data[0];?>
    <p><?php echo $data[1];?></p>
</div>
<div class="page">
    <a href="?id=<?= $id_prev;?>">上一篇</a>
    <a href="?id=<?= $id_next;?>">下一篇</a>
</div>
<div class="history">
    浏览历史：(<a href="?action=clear">清除历史</a>)
    <ul>
        <?php
        foreach ($data_history as $k=>$v)
        {
            echo "<li><a href='?id=$k'>$v</a></li>";
        }
        ?>
    </ul>
</div>