You cannot use the "basic" string manipulation functions (strcmp, strlen, etc.) because these are not unicode-aware.
However, you have the multibyte string functions family that can operate in a wide range of encodings (including UTF-8 which is the default in any sane installation nowadays).
However, you have the multibyte string functions family that can operate in a wide range of encodings (including UTF-8 which is the default in any sane installation nowadays).
[1] https://www.php.net/manual/en/ref.mbstring.php