函数uasort在PHP 5.5和PHP 7.0中的不同行为

源代码：

<?php

$arr = [
    "nominal" => [
        "before" => ["subtotal","grand_total"],"after" => [],"_code" => "nominal"
    ],"subtotal" => [
        "after" => ["nominal"],"before" => ["grand_total","shipping","freeshipping","tax_subtotal","discount","tax","weee"],"_code" => "subtotal"
    ],"shipping" => [
        "after" => ["subtotal","nominal","tax_shipping","tax"],"_code" => "shipping"
    ],"grand_total" => [
        "after" => ["subtotal","before" => [],"_code" => "grand_total"
    ],"msrp" => [
        "before" => [],"_code" => "msrp"
    ],"freeshipping" => [
        "after" => ["subtotal","nominal"],"before" => ["tax_subtotal","grand_total","discount"],"_code" => "freeshipping"
    ],"discount" => [
        "after" => ["subtotal","_code" => "discount"
    ],"tax_subtotal" => [
        "after" => ["0" => "freeshipping","1" => "subtotal","3" => "nominal"],"before" => ["tax","_code" => "tax_subtotal"
    ],"tax_shipping" => [
        "after" => ["shipping","subtotal","_code" => "tax_shipping"
    ],"tax" => [
        "after" => ["subtotal","before" => ["grand_total"],"_code" => "tax"
    ],"weee" => [
        "after" => ["subtotal","freeshipping"],"before" => ["shipping","tax_shipping"],"_code" => "weee"
    ]
];


function _compareTotals($a,$b)
{
    $aCode = $a['_code'];
    $bCode = $b['_code'];
    if (in_array($aCode,$b['after']) || in_array($bCode,$a['before'])) {
        $res = -1;
    } elseif (in_array($bCode,$a['after']) || in_array($aCode,$b['before'])) {
        $res = 1;
    } else {
        $res = 0;
    }
    echo sprintf("%s <> %s: %s",$aCode,$bCode,$res) . "n";
    return $res;
}

uasort($arr,'_compareTotals');
var_dump(array_keys($arr));

在php 5.5结果是：

freeshipping <> subtotal: 1
freeshipping <> shipping: -1
weee <> freeshipping: 1
tax <> freeshipping: 1
tax_shipping <> freeshipping: 1
tax_subtotal <> freeshipping: 1
discount <> freeshipping: 1
nominal <> freeshipping: -1
freeshipping <> grand_total: -1
msrp <> freeshipping: 0
subtotal <> msrp: 0
nominal <> subtotal: -1
tax_subtotal <> shipping: -1
weee <> tax_subtotal: 1
tax <> tax_subtotal: 1
tax_shipping <> tax_subtotal: 1
grand_total <> tax_subtotal: 1
discount <> tax_subtotal: 1
shipping <> tax_subtotal: 1
grand_total <> discount: 1
grand_total <> shipping: 1
grand_total <> tax_shipping: 1
grand_total <> tax: 1
weee <> grand_total: -1
shipping <> discount: -1
tax <> shipping: 1
tax_shipping <> shipping: 1
weee <> shipping: -1
tax_shipping <> discount: -1
tax <> tax_shipping: 1
discount <> tax_shipping: 1
tax <> discount: 1

array(11) {
  [0] =>
  string(7) "nominal"
  [1] =>
  string(8) "subtotal"
  [2] =>
  string(4) "msrp"
  [3] =>
  string(12) "freeshipping"
  [4] =>
  string(12) "tax_subtotal"
  [5] =>
  string(4) "weee"
  [6] =>
  string(8) "shipping"
  [7] =>
  string(12) "tax_shipping"
  [8] =>
  string(8) "discount"
  [9] =>
  string(3) "tax"
  [10] =>
  string(11) "grand_total"
}

在php 7.0中的结果是：

nominal <> subtotal: -1
subtotal <> shipping: -1
shipping <> grand_total: -1
grand_total <> msrp: 0
msrp <> freeshipping: 0
freeshipping <> discount: -1
discount <> tax_subtotal: 1
msrp <> tax_subtotal: 0
freeshipping <> tax_subtotal: -1
discount <> tax_shipping: 1
freeshipping <> tax_shipping: -1
tax_subtotal <> tax_shipping: -1
discount <> tax: -1
tax <> weee: 1
tax_shipping <> weee: 1
freeshipping <> weee: -1
tax_subtotal <> weee: -1

array(11) {
  [0] =>
  string(7) "nominal"
  [1] =>
  string(8) "subtotal"
  [2] =>
  string(8) "shipping"
  [3] =>
  string(11) "grand_total"
  [4] =>
  string(4) "msrp"
  [5] =>
  string(12) "freeshipping"
  [6] =>
  string(12) "tax_subtotal"
  [7] =>
  string(4) "weee"
  [8] =>
  string(12) "tax_shipping"
  [9] =>
  string(8) "discount"
  [10] =>
  string(3) "tax"
}

在PHP5中,grand_total是最后一个元素,但是在PHP7 – 否.
问题与位置msrp元素的不确定性有关.我发现一个research关于这个主题与php 5相关联.

我通过指示一个相对位置msrp解决了这个问题.但是我不知道为什么它在php5中工作,在php7中不起作用.这些是新版php或bug的功能？

加1#

问题不仅在于PHP7不知道如何排序相等的元素,例如msrp和grand_total.
如果你看货物运输和发货,那么他们是明确的,谁应该更早. PHP5解决了这个问题,而PHP7没有.