PHP-基本登录检查？

因此，我尝试使用PHP进行一次非常基本的登录：

<?php
    $username = $_POST["username"];
    $password = $_POST["password"];

    $users = array("Billy", "Bob");
    $passes = array("billy123", "pass1234");

    for ($i = 0; $i < count($users); $i++) {
        $user = $i;
        if ($username === $users[$i]) {
            if ($password === $passes[$user]) {
                echo "Logged in as " .$users[$user];
            }
        }
        else if ($username !== $users[$i] && $password !== $passes[$i]) {
            echo "Login failed";
        }
    }
?>

我不能发布照片，但它打印的是登录后的照片，因为BillyLogin就这样失败了。当我以Bob的身份登录时，它说以BobLogin的身份登录失败了，我不知道为什么，尽管我似乎无法理解。有人能解释一下发生了什么事，告诉我怎么解决吗

提前感谢。

请尝试以下代码：

$username = $_POST['user'];
$password = $_POST['pass'];
$user["Bob"]="pass";
if ($username==$user[$username]){
echo "Authenticated";
} else {
echo "bad password";
}

---

当然会发生这种情况，因为对于每个不匹配的用户名/密码组合，您都会回显“登录失败”

相反，您要做的是遍历整个数组以查看是否有匹配项，如果没有匹配项，则只在循环后输出“Login failed”

$login_successful = false;
for ($i = 0; $i < count($users); $i++) {
    if ($username === $users[$i] && $password === $passes[$i]) {
        echo "Logged in as " .$users[$i];
        $login_successful = true;
        break; // no need to continue the loop here, so we break out of it
    }
}
if (!$login_successful) {
    echo "Login failed";
}

这更简洁，也更容易循环：

$login_successful = false;
foreach ($login_credentials as $login_credential) {
    if ($username === $login_credential['username'] && $password === $login_credential["password"]) {
        echo 'Logged in as ' . $username;
        $login_successful = true;
        break; // no need to continue the loop here, so we break out of it
    }
}
if (!$login_successful) {
    echo 'Login failed';
}

---

如果您的问题是在某人经过身份验证后您没有脱离循环，那么它仍然会检查循环中的其他所有人，并在每次迭代中回显登录状态，那么这就是问题的根源。您需要的是缓存登录的用户id，如果有人登录，则设置用户id并中断循环。如果在循环之后设置了用户id，则他们将登录，否则不会登录

<?php
    $username = $_POST["username"];
    $password = $_POST["password"];

    $users = array("Billy", "Bob");
    $passes = array("billy123", "pass1234");

    $user_id=-1;

    for ($i = 0; $i < count($users); $i++)
    {
        if ($username === $users[$i] && $password === $passes[$i])
        {
            $user_id=$i;
            break;
        }
    }

    if($user_id>=0)
    {
        echo "Logged in as " .$users[$user_id];
    }else
    {
        echo "Login failed";
    }
?>

<?php
    $username = $_POST["username"];
    $password = $_POST["password"];

    $users = array("Billy", "Bob");
    $passes = array("billy123", "pass1234");

    $user_id=-1;

    for ($i = 0; $i < count($users); $i++)
    {
        if ($username === $users[$i] && $password === $passes[$i])
        {
            $user_id=$i;
            break;
        }
    }

    if($user_id>=0)
    {
        echo "Logged in as " .$users[$user_id];
    }else
    {
        echo "Login failed";
    }
?>