PHP登录脚本无法处理页面可用错误

Question

My login script displays an error message after pressing the reg button, and I can only get one echo message back.

Edit one

Is it meaningful to use elseif or should i use if ... else ...?

Edit two

After the program has finished, how can I display all available errors the program encountered under the input boxes?

---

PHP

    <?php
if($_POST['reg'] == "Registrieren"){
    $email = $_POST['email'];
    $username  = $_POST['user']; 
    $password  = $_POST['pw'];
    $passwordrep = $_POST['pwrep'];

    $email = stripslashes($email);
    $username  = stripslashes($username); 
    $password  = stripslashes($password);
    $passwordrep = stripslashes($passwordrep);

    /*if(isset($_SESSION['log']) OR $_SESSION['log'] == 1){
        $error['already_online'] = 1;
        $error['main'] = 1;
    }else*/if(empty($username)){
        $error['username_empty'] = 1;
        $error['main'] = 1;
    }else{
        if(empty($email)){
            $error['email_empty'] = 1;
            $error['main'] = 1;
        }else{
            if(empty($password) OR empty($passwordrep)){
                $error['passwords_empty'] = 1;
                $error['main'] = 1;
            }else{
                if($password == $passwordrep){
                    $error['password_confirm'] = 1;
                    $error['main'] = 1;
                }else{
                    if(strlen($username) < 6 OR strlen($username) > 64){
                        $error['username_too_short'] = 1;
                        $error['main'] = 1;
                    }else{
                        if(strlen($password) < 8 OR strlen($passwordrep) < 8){
                            $error['password_too_short'] = 1;
                            $error['main'] = 1;
                        }else{
                            if(!filter_var($email, FILTER_VALIDATE_EMAIL)){
                                $error['email_invalid'] = 1;
                                $error['main'] = 1;
                            }else{
                                if(!preg_match('/^[a-z\d]{2,64}$/i', $username)){
                                    $error['username_invalid'] = 1;
                                    $error['main'] = 1;
                                }else{
                                    if($error['main'] = 0){
                                    include_once("config/db_config.php");

                                    $email = mysqli_real_escape_string($con, $email);
                                    $username  = mysqli_real_escape_string($con, $username); 
                                    $password  = mysqli_real_escape_string($con, $password);
                                    $passwordrep = mysqli_real_escape_string($con, $passwordrep);

                                    $sql = "SELECT * FROM hp_user WHERE username = '$username'";
                                    $query = mysqli_query($con, $sql) or die($msg_signup["signup_no_connection_aviable"]);
                                    $row = mysqli_num_rows($query);
                                    if($row == 1){
                                        $error['username_exists'] = 1;
                                        $error['main'] = 1;
                                    }else{
                                        $sql = "SELECT * FROM hp_user WHERE email = '$email'";
                                        $query = mysqli_query($con, $sql) or die($msg_signup["signup_no_connection_aviable"]);
                                        $row = mysqli_num_rows($query); 
                                        if($row == 1){
                                            $error['email_exists'] = 1;
                                            $error['main'] = 1;
                                        }else{
                                            $_SESSION['log'] = 1;
                                            $_SESSION['user'] = $query->username;
                                            $_SESSION['email'] = $query->email;
                                            $add = mysqli_query($con,"INSERT INTO `agptest`.`hp_user` (`ID`, `username`, `email`, `password`, `date`, `locked`, `permission`) VALUES (NULL, '$username', '$email', '$passwordrep', CURRENT_TIMESTAMP, '0', '1');"); 
                                            $error['main'] = 0;
                                            mysqli_close();
                                            }
                                        }
                                    }
                                }
                            }
                        }
                    }
                }
            }
        }
    }
}
?>

<?php
if ($error['main'] == "0") {
    header("Location: http://www.allgameplay.de/?site=default");
}else{
    echo "<h1>Registrierung</h1>";
    echo "<form method=\"post\" action=\"index.php\">
";
    echo "Benutzername:<br><input name=\"user\" type=\"text\" size=\"30\"><br>";
    if($error['username_empty'] == 1){
        echo $msg_signup['signup_user_empty'];
    }
    if($error['username_too_short'] == 1){
        echo $msg_signup['signup_user_too_short'];
    }
    if($error['username_invalid'] == 1){
        echo "Dein Benutzername ist ungültig!";
    }
    echo "<br>E-Mail Adresse:<br><input name=\"email\" type=\"text\" size=\"30\"><br>";
    if($error['email_empty'] == 1){
        echo "Du hast keine E-Mail Adresse angegeben!";
    }
    if($error['email_invalid'] == 1){
        echo "Dies ist keine richtige E-Mail Adresse!";
    }
    echo "<br>Passwort:<br><input name=\"pw\" type=\"password\" size=\"30\"><br>";
    if($error['passwords_empty'] == 1){
        echo "Du hast kein Passwort angegeben!";
    }
    echo "<br>Passwort wiederholen:<br><input name=\"pwrep\" type=\"password\" size=\"30\"><br>";
    if($error['passwords_empty'] == 1){
        echo "Du hast kein Passwort angegeben!";
    }
    if($error['password_confirm'] == 1){
        echo "Die Passw&ouml;rter stimmen nicht überein!";
    }
    echo "<br><input type=\"submit\" name=\"reg\" value=\"Registrieren\"><br>";
}
?>

Answer 1

Edit One

Yes, you should use elseif, it makes your code look cleaner.

Edit Two

You can use GET method to return your errors with switch statement and foreach loops.

Either that or you can use jQuery to check for errors and configure it without PHP.

jQuery Validation Implementation

EDIT:

$error = array('abc','def', 'ghi');
foreach ($error as $i) {
    switch ($i) {
        case "abc":
            echo $i;
        case "def":
            echo $i;
        case "ghi":
            echo $i;
        default:
            echo "No case found!";
    }
}

I hope this clears your doubt on foreach loops.