编程面试题

1.自定义一个分页函数，传参当前页数、总页数，输出以下

1...34567...10

123456...10

//$showPage是掐头去尾的显示数量
//这个函数的重点就在于起始值和结束值的运算
function page($currentPage,$totalPages,$showPage=5)
{
        $pageStr = "";
        $from = max(1,intval($currentPage - $showPage/2)+1);
        $to = $from==1?$from + $showPage:$from + $showPage-1;
        if ($to > $totalPages) {
            $to = $totalPages;
            $from = max(1, $to - $showPage + 1);
        }

        $pageStr .= '<div class="page-nav">';
        $pageStr .= '<ul>';

        // 当当前页大于1的时候, 才会显示上一页和首页
        if($from!=1) {
            $pageStr .= '<li><a href="?p=1"> 1 </a></li>';
        }

        if ($from > 2) {
            $pageStr .= "<li><a href=?p=".($currentPage - 1)."> ... </a></li>";
        }

        for($i=$from; $i<=$to; $i++) {
            if ($i != $currentPage) {
                $pageStr .= "<li><a href='?p=".$i."'> {$i} </a></li>";
            } else {
                $pageStr .= "<li><span class='curr-page'> {$i} </span></li>";
            }
        }

        if ($to < $totalPages && $to<($totalPages-1)) {
            $pageStr .= "<li><a href=?p=".($currentPage+1)."> ... </a></li>";
        }


        // 当当前页小于总页数的时候, 才会显示下一页和尾页
        if ($to!=$totalPages) {
            $pageStr .= "<li><a href='?p=".$totalPages."'>$totalPages</a></li>";
        }

        $pageStr .= '</div>';
        $pageStr .= '</ul>';

    return $pageStr;
}
$p = isset($_GET['p'])?intval($_GET['p']):1;
echo page($p, 40);//echo