Unicode character properties

Since 5.1.0, three additional escape sequences to match generic character types are available when UTF-8 mode is selected. They are:

\p{xx}
a character with the xx property
\P{xx}
a character without the xx property
\X
an extended Unicode sequence

The property names represented by xx above are limited to the Unicode general category properties. Each character has exactly one such property, specified by a two-letter abbreviation. For compatibility with Perl, negation can be specified by including a circumflex between the opening brace and the property name. For example, \p{^Lu} is the same as \P{Lu}.

If only one letter is specified with \p or \P, it includes all the properties that start with that letter. In this case, in the absence of negation, the curly brackets in the escape sequence are optional; these two examples have the same effect:

\p{L}
\pL
Supported property codes
Property Matches Notes
C Other  
Cc Control  
Cf Format  
Cn Unassigned  
Co Private use  
Cs Surrogate  
L Letter Includes the following properties: Ll, Lm, Lo, Lt and Lu.
Ll Lower case letter  
Lm Modifier letter  
Lo Other letter  
Lt Title case letter  
Lu Upper case letter  
M Mark  
Mc Spacing mark  
Me Enclosing mark  
Mn Non-spacing mark  
N Number  
Nd Decimal number  
Nl Letter number  
No Other number  
P Punctuation  
Pc Connector punctuation  
Pd Dash punctuation  
Pe Close punctuation  
Pf Final punctuation  
Pi Initial punctuation  
Po Other punctuation  
Ps Open punctuation  
S Symbol  
Sc Currency symbol  
Sk Modifier symbol  
Sm Mathematical symbol  
So Other symbol  
Z Separator  
Zl Line separator  
Zp Paragraph separator  
Zs Space separator  

Extended properties such as InMusicalSymbols are not supported by PCRE.

Specifying case-insensitive (caseless) matching does not affect these escape sequences. For example, \p{Lu} always matches only upper case letters.

Sets of Unicode characters are defined as belonging to certain scripts. A character from one of these sets can be matched using a script name. For example:

  • \p{Greek}
  • \P{Han}

Those that are not part of an identified script are lumped together as Common. The current list of scripts is:

Supported scripts
Arabic Armenian Avestan Balinese Bamum
Batak Bengali Bopomofo Brahmi Braille
Buginese Buhid Canadian_Aboriginal Carian Chakma
Cham Cherokee Common Coptic Cuneiform
Cypriot Cyrillic Deseret Devanagari Egyptian_Hieroglyphs
Ethiopic Georgian Glagolitic Gothic Greek
Gujarati Gurmukhi Han Hangul Hanunoo
Hebrew Hiragana Imperial_Aramaic Inherited Inscriptional_Pahlavi
Inscriptional_Parthian Javanese Kaithi Kannada Katakana
Kayah_Li Kharoshthi Khmer Lao Latin
Lepcha Limbu Linear_B Lisu Lycian
Lydian Malayalam Mandaic Meetei_Mayek Meroitic_Cursive
Meroitic_Hieroglyphs Miao Mongolian Myanmar New_Tai_Lue
Nko Ogham Old_Italic Old_Persian Old_South_Arabian
Old_Turkic Ol_Chiki Oriya Osmanya Phags_Pa
Phoenician Rejang Runic Samaritan Saurashtra
Sharada Shavian Sinhala Sora_Sompeng Sundanese
Syloti_Nagri Syriac Tagalog Tagbanwa Tai_Le
Tai_Tham Tai_Viet Takri Tamil Telugu
Thaana Thai Tibetan Tifinagh Ugaritic
Vai Yi        

The \X escape matches a Unicode extended grapheme cluster. An extended grapheme cluster is one or more Unicode characters that combine to form a single glyph. In effect, this can be thought of as the Unicode equivalent of . as it will match one composed character, regardless of how many individual characters are actually used to render it.

In versions of PCRE older than 8.32 (which corresponds to PHP versions before 5.4.14 when using the bundled PCRE library), \X is equivalent to (?>\PM\pM*). That is, it matches a character without the "mark" property, followed by zero or more characters with the "mark" property, and treats the sequence as an atomic group (see below). Characters with the "mark" property are typically accents that affect the preceding character.

Matching characters by Unicode property is not fast, because PCRE has to search a structure that contains data for over fifteen thousand characters. That is why the traditional escape sequences such as \d and \w do not use Unicode properties in PCRE.

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User Contributed Notes 6 notes

up
4
mercury at caucasus dot net
4 years ago
An excellent article explaining all these properties can be found here: http://www.regular-expressions.info/unicode.html
up
3
suit at rebell dot at
4 years ago
these properties are usualy only available if PCRE is compiled with "--enable-unicode-properties"

if you want to match any word but want to provide a fallback, you can do something like that:

<?php
if(@preg_match_all('/\p{L}+/u', $str, $arr) {
 
// fallback goes here
  // for example just '/\w+/u' for a less acurate match
}
?>
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1
o_shes01 at uni-muenster dot de
3 years ago
For those who wonder: 'letter_titlecase' applies to digraphs/trigraphs, where capitalization involves only the first letter.
For example, there are three codepoints for the "LJ" digraph in Unicode:
  (*) uppercase "LJ": U+01C7
  (*) titlecase "Lj": U+01C8
  (*) lowercase "lj": U+01C9
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0
xuantoaiph at gmail dot com
11 months ago
My country, Vietnam, have our own alphabet table:
http://en.wikipedia.org/wiki/Vietnamese_alphabet
I hope PHP will support better than in Vietnamese.
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0
Yzmir Ramirez
1 year ago
If you are working with older environments you will need to first check to see if the version of PCRE will work with unicode directives described above:

<?php

// Need to check PCRE version because some environments are
// running older versions of the PCRE library
// (run in *nix environment `pcretest -C`)

$allowInternational = false;
if (
defined('PCRE_VERSION')) {
    if (
intval(PCRE_VERSION) >= 7) { // constant available since PHP 5.2.4
       
$allowInternational = true;
    }
}
?>

Now you can do a fallback regex (e.g. use "/[a-z]/i"), when the PCRE library version is too old or not available.
up
0
o_shes01 at uni-muenster dot de
3 years ago
For those who wonder: 'letter_titlecase' applies to digraphs/trigraphs, where capitalization involves only the first letter.
For example, there are three codepoints for the "LJ" digraph in Unicode:
  (*) uppercase "LJ": U+01C7
  (*) titlecase "Lj": U+01C8
  (*) lowercase "lj": U+01C9
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