$k_post = $connect->query("SELECT COUNT(*) FROM `user`")->rowCount();

  

$k_page=k_page($k_post,$set['p_str']);

$page=page($k_page);

$start=$set['p_str']*$page-$set['p_str'];



   $use = $connect->query("SELECT * FROM `user` ORDER BY `id` LIMIT $start, $set[p_str]");

   $number = 1;

   while($all = $use->fetch()){

      echo "<div class = 'menu'><a href = 'users?id=".$all['id']."'>".$number.". ".nick($all['id'])."</a></div>";

      $number++;

   }





if ($k_page>1)str("?all_users&",$k_page,$page);

class Pagination

{

    public $uri;

    public $per_page;

    public $total;

    public $count_pages;

    public $current_page;



    public function __construct($per_page, $total)

    {

        $this->uri = $this->getParams();

        $this->per_page = $per_page;

        $this->total = $total;

        $this->count_pages = $this->getCountPages();

        $this->current_page = $this->getCurrentPage();

    }



    protected function getParams()

    {

        $url = $_SERVER['REQUEST_URI'];

        $url = explode('?', $url);

        $uri = $url[0] . '?';

        if (isset($url[1]) && $url[1] != '') {

            $params = explode('&', $url[1]);

            foreach ($params as $param) {

                if (!preg_match("#page=#", $param)) $uri .= "{$param}&";

            }

        }

        return $uri;

    }



    public function getCountPages()

    {

        return ceil($this->total / $this->per_page) ?: 1;

    }



   // моя корректировка: если пользователь ввёл дичь вместо номера страницы или ввёл номер страницы, которого не может быть, то будет отправлен на ту, на которой он стал вводить дичь и в адресной строке не будет дичи

    public function getCurrentPage()

    {

        if (isset($_GET['page'])) {

            if (filter_var($_GET['page'], FILTER_VALIDATE_INT, ['options' => ['min_range' => 1, 'max_range' => $this->count_pages]])) {

                $_SESSION['page_before'] = $_GET['page'];

                return $_GET['page'];

            }

            header('location: ' . $this->uri . 'page=' . $_SESSION['page_before']);

            exit();

        }

        return 1;

    }



    public function getStart()

    {

        return ($this->current_page - 1) * $this->per_page;

    }



    public function __toString()

    {

        return $this->getHtml();

    }



    public function getHtml()

    {

        $back = $forward = $start_page = $end_page = $page2left = $page1left = $page2right = $page1right = null;

        if ($this->current_page > 1) {

            $back = "<li class='page-item'><a class='page-link' href='{$this->uri}page=" . ($this->current_page - 1) . "'>&#8249;</a></li>";

        }

        if ($this->current_page < $this->count_pages) {

            $forward = "<li class='page-item'><a class='page-link' href='{$this->uri}page=" . ($this->current_page + 1) . "'>&#8250;</a></li>";

        }

        if ($this->current_page > 3) {

            $start_page = "<li class='page-item'><a class='page-link' href='{$this->uri}page=1'>&laquo;</a></li>";

        }

        if ($this->current_page < ($this->count_pages - 2)) {

            $end_page = "<li class='page-item'><a class='page-link' href='{$this->uri}page={$this->count_pages}'>&raquo;</a></li>";

        }

        if ($this->current_page - 2 > 0) {

            $page2left = "<li class='page-item'><a class='page-link' href='{$this->uri}page=" . ($this->current_page - 2) . "'>" . ($this->current_page - 2) . "</a></li>";

        }

        if ($this->current_page - 1 > 0) {

            $page1left = "<li class='page-item'><a class='page-link' href='{$this->uri}page=" . ($this->current_page - 1) . "'>" . ($this->current_page - 1) . "</a></li>";

        }

        if ($this->current_page + 1 <= $this->count_pages) {

            $page1right = "<li class='page-item'><a class='page-link' href='{$this->uri}page=" . ($this->current_page + 1) . "'>" . ($this->current_page + 1) . "</a></li>";

        }

        if ($this->current_page + 2 <= $this->count_pages) {

            $page2right = "<li class='page-item'><a class='page-link' href='{$this->uri}page=" . ($this->current_page + 2) . "'>" . ($this->current_page + 2) . "</a></li>";

        }

        return '<nav class="mt-1"><ul class="pagination pagination-sm justify-content-center m-0">' . $start_page . $back . $page2left . $page1left . '<li class="page-item active"><a class="page-link">' . $this->current_page . '</a></li>' . $page1right . $page2right . $forward . $end_page . '</ul></nav>';

    }

}

$per_page = 5; // сколько записей на странице

$total = запрос на количество строк;

$pagination = new Pagination($per_page, $total);

$start = $pagination->getStart();

$data = запрос c limit $start, $per_page

// кидаем переменные $data и $pagination в вид



// вывод пагинации

<?php if ($pagination->count_pages > 1) : ?>

    <?= $pagination ?>

<?php endif; ?>

die(var_dump($use)); // разместить после запроса $use = ......