PHP按钮限制

Question

好的，我这里有问题。用户列“已检查”是1还是0时，它忽略IF语句并仍然添加10000点。有人能解释我为什么吗？

foreach ($users as $u) {

    if (isset($username) . $u['checked'] == 0) {

        foreach ($points as $p) {

            $username = $_SESSION['username'];

            $p = $p['points'] + 10000;

            try {
                $q = $pdo->prepare("UPDATE users SET points = ?, checked = ? WHERE username = ?");
                $q->execute(array($p, $ten, $username));
            } catch (Exception $e) {
                echo $e->getMessage();
                die();
            }

            header("Location: index.php");
        }
    } else {
        echo "Nothing";
    }
}

Answer 1

尝试使用更明确的if语句，例如

if(isset($username) && $u['checked'] == 0)

另外正如Bery在评论中所说的那样，$ username应该是$ u？