How to take a php mysql result set and transfer it into its own array

What I want to do is take the $res (result of my query) and make an $results array with the keys and values in that row. The query gets the row with the username that is the same as the one they entered in. The username is the primary key of the table.

<?php
/**
 * Created by PhpStorm.
 * User: TheWolfBadger
 * Date: 6/28/15
 * Time: 1:12 PM
 */
//MySQL Login
$fig = parse_ini_file('config.ini', true);
$host = $fig['sql']['host'];
$username = $fig['sql']['username'];
$password = $fig['sql']['password'];
$dbname = $fig['sql']['dbname'];
$port = $fig['sql']['port'];
$socket = $fig['sql']['socket'];
$con = new mysqli($host, $username, $password, $dbname, $port, $socket);
// User Functions:

function login($username, $password) {
    global $con;
    $prepared = $con->prepare("SELECT * FROM credentials WHERE username = '$username';");
    if($prepared) {
        $query = $prepared->execute();
        $res = mysql_result($query, 0); // $res[0] => username $res[2] => password $res[3] => dev $res[4] => admin $res[5] => Email $res[6] => Name $res[7] User_Image
        // How to do the above?
        if($res[1] == $password) {
            $_SESSION['username'] = $username;
            $_SESSION['password'] = $password;
            if($res[2]) {
                $_SESSION['dev'] = true;
            }
            if($res[3]) {
                $_SESSION['admin'] = true;
            }
            return true;
        }
    }
    return false;
}
function register($username, $password, $email, $user_image) {}
function user_logged_in() {
    if(!is_null($_SESSION['username'])) {
        return true;
    }
    return false;
}
function is_admin() {
    if(!is_null($_SESSION['admin'])) {
        return true;
    }
    return false;
}
function is_dev() {
    if(!is_null($_SESSION['dev'])) {
        return true;
    }
    return false;
}