php cookie验证登录的例子

php使用cookie进行登录验证。
代码如下：

<?php
// 登录验证，重置用户名
unset($username);
if ($_COOKIE['login']) {
    list($c_username,$cookie_hash) =
    split(',',$_COOKIE['login']);
    if (md5($c_username.$secret_word) == $cookie_hash) {
        $username = $c_username;
    } else {
        print "You have sent a bad cookie.";
    }
}

//登录验证
if ($username) {
    print "Welcome, $username.";
} else {
    print "Welcome, anonymous user.";
}
?>