array_diff_assoc BUG

[sujrex]

Description

The following code:

on php8.x

<?php
$array1 = array("111" => ["color" => "green"]);
$array2 = array("111" => ["color" => "green"]);
$result = array_diff_assoc($array1, $array2);
print_r($result);

Resulted in this output:

Warning: Array to string conversion in script on line 4
Warning: Array to string conversion in script on line 4
Array
(
)

But I expected this output instead:

Array
(
)

on php7.4

<?php
$array1 = array("111" => ["color" => "green"]);
$array2 = array("111" => ["color" => "green"]);
$result = array_diff_assoc($array1, $array2);
print_r($result);

Resulted in this output:

Array
(
)

期待结果为：无论那个版本，当比较数组一致时，比较不应该报错，输出位空数组即可
Expect the result to be: no matter which version, when the comparison array is consistent, the comparison should not report an error, and the output bit empty array can be

PHP Version

PHP 8.x

Operating System

windows or linux

[MorganLOCode]

As noted in the manual,

Two elements are considered equal if and only if (string) $elem1 === (string) $elem2. That is, when the string representation is the same.

So the elements being compared are cast to strings first (at least, that's what's attempted).

array_unique has the same behaviour, and it can be argued that it is this string casting that is the problem as it limits what can be compared.

[sujrex]

As noted in the manual,

Two elements are considered equal if and only if (string) $elem1 === (string) $elem2. That is, when the string representation is the same.

So the elements being compared are cast to strings first (at least, that's what's attempted).

array_unique has the same behaviour, and it can be argued that it is this string casting that is the problem as it limits what can be compared.

but
on php8.x

<?php
$array1 = array("111" => ["color" => "green"]);
$array2 = array("222" => ["color" => "green"]);
$result = array_diff_assoc($array1, $array2);
print_r($result);

Resulted in this output:

Array
(
    [111] => Array
        (
            [color] => green
        )
)

[alecpl]

I verified at https://3v4l.org/pspRm that this code and result is the same on every PHP version since 5.4. No warnings. So, I don't know what's wrong with your setup.

[sujrex]

I verified at https://3v4l.org/pspRm that this code and result is the same on every PHP version since 5.4. No warnings. So, I don't know what's wrong with your setup.

You can retry at php.net official website In addition, php8.2 installed on my Cloud Virtual Machine and windows xampp 8.2 are both reporting the same warning. your test address you provided is unclear.

[nielsdos]

Even on PHP 7.4, this causes warnings. If it does not for you, then something is different in your setup between PHP 8.x and PHP 7.4.
The reason that your example from #19217 (comment) works without warnings is because the array keys are different and therefore the values are not even getting compared, and therefore the values are not even casted to strings.
Since casting an array to a string causes a warning and returns "Array", you can't use this function for diffing nested arrays. We have array_diff_uassoc but no equivalent for a user callback for values. Therefore you'll have to make your own solution.