Safe way to get index from array with default return value even if key dose not exist

idx.php

/**
 * Get value from $array with index or indics given by $keyOrKeys.
 * @param  array $array     The array to get value from.
 * @param  mixed $keyOrKeys A single key, or a numeric array that contains multiple keys
 *                          to fetch from multidimensional array.
 *                          Key cound be either numeric or string.
 *                          If emtpy array given, the original $array will be returned.
 * @param  mixed $default   The default value to be returned if the array dose not contain
 *                          given key or midway value is not array type.
 * @return mixed            The value that associated in $array.
 */
function idx($array, $keyOrKeys, $default = null) {
    if (!is_array($keyOrKeys)) {
        $key = $keyOrKeys;
        return isset($array[$key])? $array[$key] : $default;
    }

    $keys = $keyOrKeys;
    $count = count($keys);

    $i = 0;
    while ($i < $count && is_array($array)) {
        $key = $keys[$i];
        if (!isset($array[$key])) {
            break;
        }
        $array = $array[$key];
        $i++;
    }

    if ($i == $count) {
        return $array;
    }

    return $default;
}


/*
function idxTEST() {
    $a = array(0,1,2,3,4, 
        'hello' => 'world', 
        'a' => array(0,1,2,3,4,
                'welcome' => 'back'
            ),
        );
    echo '<pre>';
    // Test on single-index
    var_dump(idx($a, 0)); // 0
    var_dump(idx($a, 7)); // null
    var_dump(idx($a, 7, 7)); // 7
    var_dump(idx($a, 'hello')); // world

    // Test on multi-index
    var_dump(idx($a, array('a', 0))); // 0
    var_dump(idx($a, array('a', 7), 7)); // 7
    var_dump(idx($a, array('a', 'welcome'))); // back


    echo '</pre>';
}

idxTEST();
*/