无法转换为小写 - 不工作

unable to convert to lowercase - not working

我的页面上有以下代码,但即使用户名和密码以小写形式输入,我也想登录,我在网上看过,答案答案似乎表明 strtolower 可以工作,但它不起作用为我工作,有人可以看看吗?

感谢您的帮助!

<?php
    $error = "";
    if(isset($_POST['username'],$_POST['password'])){
        $user = array(
                        "user" => "Demo",
                        "pass"=>"Demo"          
                );
        $username = strtolower($_POST['username']);
        $pass = strtolower($_POST['password']);
        if($username == $user['user'] && $pass == $user['pass']){
            session_start();
            $_SESSION['simple_login'] = $username;
            echo '{"error":0}';
        }else{
            echo '{"error":1}';
        }
        exit();
    }
?>

虽然这是一种方法,但您可能不应该这样做,这并不安全.为什么 username/password 不区分大小写?

<?php
    $error = "";
    if(isset($_POST['username'],$_POST['password'])){
        $user = array(
                        "user" => strtolower("Demo"),
                        "pass"=> strtolower("Demo")          
                );
        $username = strtolower($_POST['username']);
        $pass = strtolower($_POST['password']);
        if($username == $user['user'] && $pass == $user['pass']){
            session_start();
            $_SESSION['simple_login'] = $username;
            echo '{"error":0}';
        }else{
            echo '{"error":1}';
        }
        exit();
    }
?>