> I like to elaborate on Nikitas response: I don't think a mb_str_contains is
> necessary, because the proposed function does not behave differently, if
> the input strings are multibyte strings.
This is not true for all character encodings. For UTF-8 it is correct,
but consider for example the Japanese encoding Shift_JIS, where the
second byte of a multi-byte character can be a valid first byte of a
single-byte character. str_contains() would have incorrect behaviour for