php - PHP 中是否保证关联数组的顺序？

Question

当我在 php 中对关联数组执行 foreach 循环时，它的执行顺序就是它定义的顺序。

例如:

$arr = array("z" => "z", "a" => "a", "b" => "b");

foreach($arr as $key => val)
  print("$key: $val\n");

输出:

z: z
a: a
b: b

鉴于

$arr = array("a" => "a", "b" => "b", "z" => "z");

输出:

a: a
b: b
z: z

那么我的问题是:这种行为是在规范级别定义的吗？我可以合理地确定这种行为在未来的 PHP 版本中不会改变吗？

Answer 1

来自PHP Manual

An array in PHP is actually an ordered map. A map is a type that associates values to keys. This type is optimized for several different uses; it can be treated as an array, list (vector), hash table (an implementation of a map), dictionary, collection, stack, queue, and probably more.

和

Arrays are ordered. The order can be changed using various sorting functions.

因此您可以确定(至少目前)订单将得到维持。如果此行为发生变化，我会感到非常惊讶，因为它已明确说明，因此将会有大量代码依赖它。