if语句中"header"的行为

Question

这是我检查访问的代码.

$query = "SELECT user_table.status, expire FROM user_table WHERE username = ?";

if($stmt = $mysqli->prepare($query)){
    $username = phpCAS::getAttribute('uid');
    $stmt->bind_param('s', $username);
    $stmt->execute();
    $stmt->store_result();
    $returned_amount = $stmt->num_rows;


    if($returned_amount>1)
        die("To many user names exists for you!");
    else if(empty($returned_amount))
        header("Location: /101/index.php?type=nouser");


    $stmt->bind_result($status, $expire);
    $stmt->fetch();
    $stmt->free_result();
    $stmt->close();

    if($expire != '0000-00-00 00:00:00' && strtotime($expire) <= time())
        header('Location: /101/index.php?type=expired');

    $access = $status;

}else die("Failed to prepare!");

?>

然而,当$returned_amount == 0.

它没有击中 header("Location: /101/index.php?type=nouser");

如果我将代码更改为以下代码,则可以解决问题,但我不明白为什么更改代码会有所帮助.

if($returned_amount>1)
    die("To many user names exists for you!");
else if(empty($returned_amount)){
    header("Location: /101/index.php?type=nouser");
    exit();
}

如果我删除了exit();,标题将不会被执行.

Answer 1

刚开始使用header()并不能意味着该代码将停止执行.每当使用header()重定向时,您需要显式调用exit()以停止执行脚本.