//分页函数 第一页: url/1 第二页: url/2
function pages($url, $totalnum, $page, $pagesize = 20) {
    $urladd = '';
    $url .= '/';

    $totalpage = ceil($totalnum / $pagesize);
    if($totalpage < 2) return '';
    $page = min($totalpage, $page);
    $shownum = 5;   // 显示多少个页 * 2

    $start = max(1, $page - $shownum);
    $end = min($totalpage, $page + $shownum);

    // 不足 $shownum，补全左右两侧
    $right = $page + $shownum - $totalpage;
    $right > 0 && $start = max(1, $start -= $right);
    $left = $page - $shownum;
    $left < 0 && $end = min($totalpage, $end -= $left);

    $s = '';
    $page != 1 && $s .= '◀';
    if($start > 1) $s .= '1 '.($start > 2 ? '... ' : '').'';
    for($i=$start; $i 1 ? '... ' : '').$totalpage.'';
    $page != $totalpage && $s .= '▶';
    return $s;
}


function mid($n, $min, $max) {
    if($n < $min) return $min;
    if($n > $max) return $max;
    return $n;
}

function page($page, $n, $pagesize) {
    $total = ceil($n / $pagesize);
    $total < 1 AND $total = 1;
    return mid($page, 1, $total);
}

$pagesize = 20;    //每页显示多少用户
$n = user_count();      //总用户数
$page = page($page, $n, $pagesize);  //当前页数
$userlist = user_find($page, $pagesize);  //查找出当前页的用户
//html部分，分页效果，直接渲染到页面即可
$pagehtml = pages(url前缀, $n, $page, $pagesize);