how to get wordpress user id when user register

Question

im creating wordpress user using wp_create_user() function and when user creating i want to add that users userid to custom table,

this is the way i tried

add_action( 'user_register', 'atuser_info');
function atuser_info( $user_id ) {          
    global $wpdb; 
    //$prefix=$wpdb->prefix;                
    $query_userinfo = "INSERT INTO user_info (id,fname,lname,address_1) VALUES      (".$user_id.",".$_POST['fname'].",".$_POST['lname'].",".$_POST['address_1_step2'].")";
    $wpdb->query($query_userinfo);
}

Answer 1

If wp_create_user executes successfully, it will return the id of the created user. [Codex]

Here it is in action with an error handler.

$user_id = wp_create_user();

if( is_wp_error($user_id) ) {
    echo $user_id->get_error_message();
} else {
    //add into custom table
    echo $user_id;
}

Answer 2

// $user_login is the username
// $user_email is the email address

$user_id = register_new_user($user_login, $user_email);

if( $user_id ) {
echo $user_id;
// add to your database
}
else {
echo $user_id->get_error_message();
}