自从 PHP 4.4.0 和 5.1.0， 三个额外的转义序列在选用 UTF-8模式时用于匹配通用字符类型。他们是：
上面 xx 代表的属性名用于限制 Unicode 通常的类别属性。 每个字符都有一个这样的确定的属性，通过两个缩写的字母指定。 为了与 perl 兼容， 可以在左花括号 { 后面增加 ^ 表示取反。比如： \p{^Lu} 就等同于 \P{Lu}。
如果通过 \p 或 \P 仅指定了一个字母，它包含所有以这个字母开头的属性。 在这种情况下，花括号的转义序列是可选的。
\p{L}
\pL
| 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 |
InMusicalSymbols 等扩展属性在 PCRE 中不支持
指定大小写不敏感匹配对这些转义序列不会产生影响，比如， \p{Lu} 始终匹配大写字母。
Unicode 字符集在具体文字中定义。使用文字名可以匹配这些字符集中的一个字符。例如：
不在确定文字中的则被集中到 Common。当前的文字列表中有：
| 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 |
\X 转义匹配任意数量的 Unicode 字符。 \X 等价于 (?>\PM\pM*)
也就是说，它匹配一个没有 ”mark” 属性的字符，紧接着任意多个由 ”mark” 属性的字符。 并将这个序列认为是一个原子组(详见下文)。 典型的有 ”mark” 属性的字符是影响到前面的字符的重音符。
用 Unicode 属性来匹配字符并不快， 因为 PCRE 需要去搜索一个包含超过 15000 字符的数据结构。 这就是为什么在 PCRE中 要使用传统的转义序列\d、 \w 而不使用 Unicode 属性的原因。
o_shes01 at uni-muenster dot de (2011-01-22 06:23:58)
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
o_shes01 at uni-muenster dot de (2011-01-21 10:08:48)
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
mercury at caucasus dot net (2010-05-08 10:32:29)
An excellent article explaining all these properties can be found here: http://www.regular-expressions.info/unicode.html
suit at rebell dot at (2010-03-01 05:13:08)
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
}
?>