Custom registration

registration.php

	<?php
$err = '';
$success = '';

global $wpdb, $PasswordHash, $current_user, $user_ID;

if (isset($_POST['task']) && $_POST['task'] == 'register') {
    $first_name = $wpdb->escape(trim($_POST['first_name']));
    $last_name = $wpdb->escape(trim($_POST['last_name']));
    $email = $wpdb->escape(trim($_POST['email']));
    $pwd1 = $wpdb->escape(trim($_POST['pwd1']));
    $middle_name = $wpdb->escape(trim($_POST['middle_name']));
    $scientific_research = $wpdb->escape(trim($_POST['scientific_research']));
    $specialty = $wpdb->escape(trim($_POST['specialty']));
    $city = $wpdb->escape(trim($_POST['city']));

    // $username = $wpdb->escape(trim($_POST['username']));
    if ($email == "" || $pwd1 == "" || $first_name == "" || $last_name == "") {
        $err = 'Please don\'t leave the required fields.';
    } else if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
        $err = 'Invalid email address.';
    } else if (email_exists($email)) {
        $err = 'Email already exist.';
    } else {
        $user_id = wp_insert_user(array('first_name' => apply_filters('pre_user_first_name', $first_name), 'last_name' => apply_filters('pre_user_last_name', $last_name), 'user_pass' => apply_filters('pre_user_user_pass', $pwd1), 'user_login' => apply_filters('pre_user_user_email', $email), 'user_email' => apply_filters('pre_user_user_email', $email), 'role' => 'subscriber'));
        if (is_wp_error($user_id)) {
            $err = 'Error on user creation.';
            die($err);
        } else {
            update_field('middle_name', $middle_name, 'user_' . $user_id);
            update_field('scientific_research', $scientific_research, 'user_' . $user_id);
            update_field('specialty', $specialty, 'user_' . $user_id);
            update_field('city', $city, 'user_' . $user_id);
            do_action('user_register', 'user_' . $user_id);
            $success = 'You\'re successfully register';
        }

    }

}

?>