<?php
    $islogin = false;
    if (isset($_GET["kod"]) && $_GET["kod"] == 1111 ) {
        echo "Üdvözöllek".$_GET["nev"];
        $islogin = true;
    }
?>


<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>PHP form</title>
</head>
<body>
    <?php 
        if ($islogin == "false") { 
    ?>
        <form>
            <input type="text" name="nev" title="Adja meg a nevet"><br>
            <input type="number" name="kod" min="1000" max="5000" title="Adja meg a kódot"><br>
            <input type="submit" value="Belépés">
        </form>
    <?php
        }
    ?>
</body>
</html>