wordpress user registration and login code example

Example: wordpress register user php

<php 
        // register
        
        $user = (isset($_POST['username']) ? $_POST['username'] : '');
        $pass = (isset($_POST['password']) ? $_POST['password'] : '');
        $email = (isset($_POST['email']) ? $_POST['email'] : '');

        if (!username_exists($user)  && !email_exists($email)) {
            $user_id = wp_create_user($user, $pass, $email);
            if (!is_wp_error($user_id)) {
                //user has been created
                $user = new WP_User($user_id);
                $user->set_role('do');
                //Redirect
                wp_redirect('URL_where_you_want_redirect');
                exit;
            } else {
                //$user_id is a WP_Error object. Manage the error
            }
        }else{
            // user exist
        }
?>