Untitled

<!DOCTYPE html>
<html>
    <head>
    </head>
    <body>
        <form method="POST" action="index.php">
            <input placeholder="Email" type="text" name="email">
            <input placeholder="Age" type="text" name="age">
            <input placeholder="Password" type="password" name="password">
            <input type="submit">
        </form>
    </body>
</html>

<?php
$email = $_POST["email"];
$age = $_POST["age"];
$password = $_POST["password"];

$condition = (isset($email) && $age >= 16 && $age < 100 && strlen($password) > 5 && strlen($password) < 25);

if($condition) {
    $dbopen = fopen("db.txt", "a") or die("something wrong with file system...");

    fwrite($dbopen, $age . "\n");
    fwrite($dbopen, $email . "\n");
    fwrite($dbopen, $password . "\n");

    fclose($dbopen);
    echo "All right";
} else {
    echo "WRYYYYY";
}
?>