Compare Dynamic Multidimensional Arrays - php

Question

I have two multidimensional dynamic arrays like so in PHP:
$old = array(
"meta_data" => array(
"page_title" => "Test1",
"page_description" => "Test2",
"page_keywords" => "Test3"
),
"content" => array(
"page_header_one" => "1",
"page_content_one" => "2",
"page_header_two" => "3",
"page_content_two" => "4",
"page_header_three" => "5"
),
);
$new = array(
"meta_data" => array(
"page_title" => "Test1",
"page_description" => "Test2",
"page_keywords" => "Test3324"
),
"content" => array(
"page_header_one" => "124",
"page_content_one" => "243",
"page_header_two" => "343"
),
);
I'm struggling to compare these as they're dynamic, e.g. the keys change. What I'm aiming to do is compare the arrays, find out what's changed, leave out keys that don't match, and only add the changes to the new array.
The only things that will be constant are "meta_data" and "content"
So for example in $old we have 5 items in the content array, but in the $new array we only have 3 items (3 changed items), so the new array would have 3 content items.
Is there a way to do this I can't for the life in me figure out how?
Final array should look like so:
$final = array(
"meta_data" => array(
"page_keywords" => "Test3324"
),
"content" => array(
"page_header_one" => "124",
"page_content_one" => "243",
"page_header_two" => "343"
),
);

Answer 1

Maybe it can be done easier, but I think this will do the job:
<?php
$newArray = [];
foreach($old['meta_data'] as $key => $value) {
if(array_key_exists($key, $new['meta_data'])) {
if($new['meta_data'][$key] == $old['meta_data'][$key]) {
$newArray['meta_data'][$key] = $value;
}
}
}
foreach($old['content'] as $key => $value) {
if(array_key_exists($key, $new['content'])) {
if($new['content'][$key] == $old['content'][$key]) {
$newArray['content'][$key] = $value;
}
}
}
You can also make the top key dynamic, so content and meta_data are dynamic as well, like this:
foreach($old as $topKey => $subArray) {
if(array_key_exists($topKey, $new)) {
foreach($subArray as $key => $value) {
if(array_key_exists($key, $new[$topKey])) {
if($new[$topKey][$key] == $old[$topKey][$key]) {
$newArray[$topKey][$key] = $value;
}
}
}
}
}
I haven't tested it. But I think you'll get the gist.

Answer 2

The only things that will be constant are "meta_data" and "content"
Given this thing in mind, the solution to your problem would be to use array_diff() function like this:
$final = array();
$final['meta_data'] = array_diff($new['meta_data'], $old['meta_data']);
$final['content'] = array_diff($new['content'], $old['content']);
// display $final array
var_dump($final);
Here's a live demo

Answer 3

You can simply use the PHP array_diff() function.
$final = array_diff($new, $old);