PHP function in_array doesn't recognize diacritic - php

Question

I have a code that runs through files and getting all images.
$img = '/srv/www/wordpress-default/public_html/wp-content/uploads/2018/07/2018_07_DogOwner_VS_CatOwner_655x368_NL-500x281.jpg';
$dir = preg_replace('#[^/]*$#', '', $img);
$image_files = scandir($dir);
$image_name = #array_pop(explode('/', $img));
$find = $image_name;
var_dump(in_array($find, $image_files));
In this example I run only through one image. This code returns true. The problem is when I have an image that has for example german signs (hundezubehör-für-sommer.jpg).
$img = '/srv/www/wordpress-default/public_html/wp-content/uploads/2018/07/hundezubehör-für-sommer.jpg';
This returns false. Any ideas why this doesn't work?
EDITED:
I have asked this question few days ago: How to find a shortest name (string) of the same image with different naming. The solution to this is here: https://3v4l.org/T7lfU. The problem I think is when I run the code from scandir then It can't find the diacritic.

Answer 1

The in_array function works despite the strings alphabet. I guest the problem happens because your PHP file and filesystem use different encodings therefore the value read by scandir has another encoding therefore it differs from the $img value written in the code.
Try to convert the encoding of the scandir result to make it match the PHP file encoding. For example:
// ...
$image_files = scandir($dir);
foreach ($image_files as &$file) {
$file = mb_convert_encoding($file, 'UTF-8', 'Windows-1251');
}
// ...
var_dump(in_array($find, $image_files));
Replace UTF-8 with the PHP file encoding and Windows-1251 with your filesystem encoding.

Answer 2

The problem is with storing multi-byte characters like ö and ü into a PHP file.
You can try interpreting the string as multi-byte:
$img = utf8_encode('/srv/www/wordpress-default/public_html/wp-content/uploads/2018/07/hundezubehör-für-sommer.jpg');
Encoding, then decoding to make it safer:
$img = html_entity_decode('/srv/www/wordpress-default/public_html/wp-content/uploads/2018/07/hundezubehör-für-sommer.jpg');
Or backslash the entities:
$img = "/srv/www/wordpress-default/public_html/wp-content/uploads/2018/07/hundezubeh\303\266r-f\303\274r-sommer.jpg";