checkLogin.php #1 [Mike M. tutorial]

<?php

    @$getWarningID = strip_tags($_GET['id']);
    $warnings = false;

    switch($getWarningID){
        case 1:  //wrong username + password combination
            $warning = "Wrong Username and/or Password!";
            break;
        case 2: //username is not found
            $warning = "The filled in username is not found!";
            break;
        case 3: //username and/or password might be empty
            $warning = "Username and/or Password not filled in!";
            break;
        case 4: //username is not alphanumeric OR haven't got the correct length
            $warning = "Username has the incorrect length and it only allows ALPHANUMERIC characters!";
            break;
        case 5: //password haven't got the correct length, or does not contact a-z A-Z 0-9 ! @ # $ % ^ & *
            $warning = "Password has the incorrect length or the password doesn't match the allowed characters<br />\n<strong>a-z A-Z 0-9 ! @ # $ % ^ & *</strong>";
            break;
        default:  //there is no warning
            //$warning = "none";
            unset($warning);
            break;
    }

    if(!empty($getWarningID) && !empty($warning)){
    ?>
    <p>
        <strong>WARNING!:</strong><br/>
        <?php
            echo($warning);
        ?>
    </p>
    <hr>
    <?php
    }
    ?>

    <p>
        <form action="doLogin.php" method="POST">
            Username: <input type="username" name="username" value="" /><br />
            Password: <input type="password" name="password" value="" />
            <input type="submit" name="login" value="Login" /><br />
            <strong>-=Passwords may only contain the following=-</strong>
            <ul>
                <li>Minimal of 6 Characters!</li>
                <li>Maximum of 20 Characters!</li>
                <li>Lowercase and/or Uppercase alphabetic Characters</li>
                <li>The following special characters: ! @ # $ % ^ & *</li>
            </ul>
        </form>
    </p>