EMS快递单号生成算法

<?php

function emsnum($ems, $num) {

    $fri = substr($ems, 2, 8);

    $head = substr($ems, 0, 2);

    $tail = substr($ems, -2);

    for ($i = 1; $i <= $num; $i++) {

        $num3 = substr($fri, 0, 1);

        $num4 = substr($fri, 1, 1);

        $num5 = substr($fri, 2, 1);

        $num6 = substr($fri, 3, 1);

        $num7 = substr($fri, 4, 1);

        $num8 = substr($fri, 5, 1);

        $num9 = substr($fri, 6, 1);

        $num0 = substr($fri, 7, 1);

        $mid = 8 * $num3 + 6 * $num4 + 4 * $num5 + 2 * $num6 + 3 * $num7 + 5 * $num8 + 9 * $num9 + 7 * $num0;

        $res = 11 - ($mid % 11);

        if ($res == 10) {

            $res = 0;

        }

        if ($res == 11) {

            $res = 5;

        }

        $emsres[$i] = $head . $fri . $res . $tail;

        $fri+= 1;

        $len = strlen($fri);

        if ($len < 8) {

            for ($j = $len; $j < 8; $j++) {

                $fri = "0" . $fri;

            }

        }

    }

    return $emsres;

}

$arr = emsnum("1014662951580", "20");

echo "<pre>";

var_dump($arr);

die;

?>