Convert a String into an Array of Characters - multi-byte

Question

Assuming that in 2019 every solution which is not UNICODE-safe is wrong. What is the best way to convert a string to array of UNICODE characters in PHP?

Obviously th

Answer 1

Just pass an empty pattern with the PREG_SPLIT_NO_EMPTY flag. Otherwise, you can write a pattern with \X (unicode dot) and \K (restart fullstring match). I'll include a mb_split() call and a preg_match_all() call for completeness.

Code: (Demo)

$string='先秦兩漢';
var_export(preg_split('~~u', $string, 0, PREG_SPLIT_NO_EMPTY));
echo "\n---\n";
var_export(preg_split('~\X\K~u', $string, 0, PREG_SPLIT_NO_EMPTY));
echo "\n---\n";
var_export(preg_split('~\X\K(?!$)~u', $string));
echo "\n---\n";
var_export(mb_split('\X\K(?!$)', $string));
echo "\n---\n";
var_export(preg_match_all('~\X~u', $string, $out) ? $out[0] : []);

All produce::

array (
  0 => '先',
  1 => '秦',
  2 => '兩',
  3 => '漢',
)

From https://www.regular-expressions.info/unicode.html:

How to Match a Single Unicode Grapheme

Matching a single grapheme, whether it's encoded as a single code point, or as multiple code points using combining marks, is easy in Perl, PCRE, PHP, Boost, Ruby 2.0, Java 9, and the Just Great Software applications: simply use \X.

You can consider \X the Unicode version of the dot. There is one difference, though: \X always matches line break characters, whereas the dot does not match line break characters unless you enable the dot matches newline matching mode.

---

UPDATE, DHarman has brought to my attention that mb_str_split() is now available from PHP7.4.

The default length parameter of the new function is 1, so the length parameter can be omitted for this case.

https://wiki.php.net/rfc/mb_str_split

Dharman's demo: https://3v4l.org/M85Fi/rfc#output