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In-Reply-To: <8CFCFE96-E2B7-456B-85A3-8737754C59D6@benramsey.com>
Date: Sun, 23 Jun 2019 17:46:23 +0200
Message-ID: <CAF+90c_yNYSr65Atf_N7Ytg1fOAYgCpM1HG3DcquhOqi3jytqw@mail.gmail.com>
To: Ben Ramsey <ben@benramsey.com>
Cc: Rowan Collins <rowan.collins@gmail.com>, PHP internals <internals@lists.php.net>
Content-Type: multipart/alternative; boundary="000000000000fcd528058bff9914"
Subject: Re: [PHP-DEV] [RFC] Desire to move RFC add_str_begin_and_end_functions
 to a vote
From: nikita.ppv@gmail.com (Nikita Popov)

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On Sun, Jun 23, 2019 at 5:30 PM Ben Ramsey <ben@benramsey.com> wrote:

> > On Jun 23, 2019, at 05:35, Rowan Collins <rowan.collins@gmail.com>
> wrote:
> >
> > On 22 June 2019 20:56:24 BST, Ben Ramsey <ben@benramsey.com> wrote:
> >> Perhaps it would only be an issue with the case-insensitive versions,
> >> as Nikita points out? If so, can someone provide some example strings
> >> where an mb_starts_with_ci() would return true, while
> >> str_starts_with_ci() would return false?
> >
> >
> > That's easy: any character that has a lower- and uppercase form, and is
> not represented as one byte in the target encoding. For that matter, any
> such character in the non-ASCII section of a single-byte encoding, since =
a
> non-mbstring case insensitive flag would presumably leave everything othe=
r
> than ASCII letters untouched.
> >
> > So, any non-Latin script, like Greek or Cyrillic; any accented
> characters, unless you're lucky and they're represented by ASCII-letter
> plus combining modifier; the Turkish "i", which if I remember rightly has
> three forms not two; and so on.
>
>
> According to Google, "=C4=B0yi ak=C5=9Famlar=E2=80=9D is the Turkish phra=
se for =E2=80=9CGood
> evening=E2=80=9D (Turkish speakers, please correct me, if this wrong). Ho=
wever,
> using the existing mb_* functions, I can=E2=80=99t get mb_stripos() to re=
turn 0
> when trying to see if the string =E2=80=9C=C4=B0YI AK=C5=9EAMLAR=E2=80=9D=
 begins with =E2=80=9Ci=CC=87yi.=E2=80=9D
>
> I=E2=80=99m just using UTF-8, so maybe there=E2=80=99s an encoding issue =
here?
>
> $string =3D '=C4=B0yi ak=C5=9Famlar';
> $upper =3D mb_strtoupper($string);
> $lowerChars =3D mb_strtolower(mb_substr($string, 0, 3));
>
> var_dump($string, $upper, $lowerChars);
> var_dump(mb_stripos($upper, $lowerChars));
>

The reason why this doesn't work is that mb_stripos internally performs a
simple case fold, while a full case fold would be needed in this case
(Turkish i is hard). It's a bit tricky due to the need to remap character
offsets.

Nikita

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