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<html>
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<head>
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<title>pcresyntax specification</title>
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</head>
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<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
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<h1>pcresyntax man page</h1>
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<p>
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Return to the <a href="index.html">PCRE index page</a>.
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</p>
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<p>
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This page is part of the PCRE HTML documentation. It was generated automatically
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from the original man page. If there is any nonsense in it, please consult the
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man page, in case the conversion went wrong.
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<br>
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<ul>
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<li><a name="TOC1" href="#SEC1">PCRE REGULAR EXPRESSION SYNTAX SUMMARY</a>
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<li><a name="TOC2" href="#SEC2">QUOTING</a>
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<li><a name="TOC3" href="#SEC3">CHARACTERS</a>
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<li><a name="TOC4" href="#SEC4">CHARACTER TYPES</a>
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<li><a name="TOC5" href="#SEC5">GENERAL CATEGORY PROPERTY CODES FOR \p and \P</a>
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<li><a name="TOC6" href="#SEC6">SCRIPT NAMES FOR \p AND \P</a>
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<li><a name="TOC7" href="#SEC7">CHARACTER CLASSES</a>
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<li><a name="TOC8" href="#SEC8">QUANTIFIERS</a>
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<li><a name="TOC9" href="#SEC9">ANCHORS AND SIMPLE ASSERTIONS</a>
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<li><a name="TOC10" href="#SEC10">MATCH POINT RESET</a>
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<li><a name="TOC11" href="#SEC11">ALTERNATION</a>
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<li><a name="TOC12" href="#SEC12">CAPTURING</a>
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<li><a name="TOC13" href="#SEC13">ATOMIC GROUPS</a>
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<li><a name="TOC14" href="#SEC14">COMMENT</a>
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<li><a name="TOC15" href="#SEC15">OPTION SETTING</a>
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<li><a name="TOC16" href="#SEC16">LOOKAHEAD AND LOOKBEHIND ASSERTIONS</a>
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<li><a name="TOC17" href="#SEC17">BACKREFERENCES</a>
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<li><a name="TOC18" href="#SEC18">SUBROUTINE REFERENCES (POSSIBLY RECURSIVE)</a>
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<li><a name="TOC19" href="#SEC19">CONDITIONAL PATTERNS</a>
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<li><a name="TOC20" href="#SEC20">BACKTRACKING CONTROL</a>
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<li><a name="TOC21" href="#SEC21">NEWLINE CONVENTIONS</a>
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<li><a name="TOC22" href="#SEC22">WHAT \R MATCHES</a>
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<li><a name="TOC23" href="#SEC23">CALLOUTS</a>
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<li><a name="TOC24" href="#SEC24">SEE ALSO</a>
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<li><a name="TOC25" href="#SEC25">AUTHOR</a>
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<li><a name="TOC26" href="#SEC26">REVISION</a>
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</ul>
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<br><a name="SEC1" href="#TOC1">PCRE REGULAR EXPRESSION SYNTAX SUMMARY</a><br>
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<P>
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The full syntax and semantics of the regular expressions that are supported by
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PCRE are described in the
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<a href="pcrepattern.html"><b>pcrepattern</b></a>
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documentation. This document contains just a quick-reference summary of the
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syntax.
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</P>
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<br><a name="SEC2" href="#TOC1">QUOTING</a><br>
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<P>
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<pre>
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\x where x is non-alphanumeric is a literal x
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\Q...\E treat enclosed characters as literal
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</PRE>
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</P>
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<br><a name="SEC3" href="#TOC1">CHARACTERS</a><br>
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<P>
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<pre>
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\a alarm, that is, the BEL character (hex 07)
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\cx "control-x", where x is any character
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\e escape (hex 1B)
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\f formfeed (hex 0C)
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\n newline (hex 0A)
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\r carriage return (hex 0D)
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\t tab (hex 09)
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\ddd character with octal code ddd, or backreference
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\xhh character with hex code hh
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\x{hhh..} character with hex code hhh..
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</PRE>
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</P>
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<br><a name="SEC4" href="#TOC1">CHARACTER TYPES</a><br>
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<P>
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<pre>
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. any character except newline;
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in dotall mode, any character whatsoever
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\C one byte, even in UTF-8 mode (best avoided)
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\d a decimal digit
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\D a character that is not a decimal digit
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\h a horizontal whitespace character
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\H a character that is not a horizontal whitespace character
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\p{<i>xx</i>} a character with the <i>xx</i> property
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\P{<i>xx</i>} a character without the <i>xx</i> property
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\R a newline sequence
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\s a whitespace character
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\S a character that is not a whitespace character
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\v a vertical whitespace character
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\V a character that is not a vertical whitespace character
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\w a "word" character
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\W a "non-word" character
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\X an extended Unicode sequence
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</pre>
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In PCRE, \d, \D, \s, \S, \w, and \W recognize only ASCII characters.
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</P>
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<br><a name="SEC5" href="#TOC1">GENERAL CATEGORY PROPERTY CODES FOR \p and \P</a><br>
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<P>
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<pre>
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C Other
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Cc Control
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Cf Format
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Cn Unassigned
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Co Private use
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Cs Surrogate
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L Letter
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Ll Lower case letter
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Lm Modifier letter
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Lo Other letter
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Lt Title case letter
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Lu Upper case letter
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L& Ll, Lu, or Lt
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M Mark
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Mc Spacing mark
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Me Enclosing mark
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Mn Non-spacing mark
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N Number
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Nd Decimal number
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Nl Letter number
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No Other number
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P Punctuation
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Pc Connector punctuation
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Pd Dash punctuation
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Pe Close punctuation
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Pf Final punctuation
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Pi Initial punctuation
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Po Other punctuation
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Ps Open punctuation
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S Symbol
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Sc Currency symbol
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Sk Modifier symbol
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Sm Mathematical symbol
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So Other symbol
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Z Separator
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Zl Line separator
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Zp Paragraph separator
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Zs Space separator
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</PRE>
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</P>
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<br><a name="SEC6" href="#TOC1">SCRIPT NAMES FOR \p AND \P</a><br>
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<P>
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Arabic,
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Armenian,
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Balinese,
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Bengali,
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Bopomofo,
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Braille,
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Buginese,
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Buhid,
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Canadian_Aboriginal,
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Cherokee,
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Common,
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Coptic,
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Cuneiform,
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Cypriot,
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Cyrillic,
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Deseret,
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Devanagari,
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Ethiopic,
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Georgian,
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Glagolitic,
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Gothic,
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Greek,
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Gujarati,
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Gurmukhi,
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Han,
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Hangul,
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Hanunoo,
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Hebrew,
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Hiragana,
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Inherited,
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Kannada,
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Katakana,
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Kharoshthi,
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Khmer,
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Lao,
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Latin,
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Limbu,
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Linear_B,
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Malayalam,
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Mongolian,
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Myanmar,
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New_Tai_Lue,
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Nko,
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Ogham,
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Old_Italic,
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Old_Persian,
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Oriya,
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Osmanya,
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Phags_Pa,
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Phoenician,
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Runic,
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Shavian,
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Sinhala,
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Syloti_Nagri,
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Syriac,
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Tagalog,
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Tagbanwa,
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Tai_Le,
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Tamil,
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Telugu,
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Thaana,
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Thai,
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Tibetan,
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Tifinagh,
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Ugaritic,
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Yi.
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</P>
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<br><a name="SEC7" href="#TOC1">CHARACTER CLASSES</a><br>
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<P>
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<pre>
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[...] positive character class
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[^...] negative character class
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[x-y] range (can be used for hex characters)
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[[:xxx:]] positive POSIX named set
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[[:^xxx:]] negative POSIX named set
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alnum alphanumeric
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alpha alphabetic
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ascii 0-127
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blank space or tab
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cntrl control character
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digit decimal digit
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graph printing, excluding space
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lower lower case letter
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print printing, including space
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punct printing, excluding alphanumeric
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space whitespace
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upper upper case letter
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word same as \w
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xdigit hexadecimal digit
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</pre>
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In PCRE, POSIX character set names recognize only ASCII characters. You can use
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\Q...\E inside a character class.
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</P>
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<br><a name="SEC8" href="#TOC1">QUANTIFIERS</a><br>
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<P>
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<pre>
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? 0 or 1, greedy
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?+ 0 or 1, possessive
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?? 0 or 1, lazy
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* 0 or more, greedy
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*+ 0 or more, possessive
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*? 0 or more, lazy
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+ 1 or more, greedy
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++ 1 or more, possessive
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+? 1 or more, lazy
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{n} exactly n
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{n,m} at least n, no more than m, greedy
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{n,m}+ at least n, no more than m, possessive
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{n,m}? at least n, no more than m, lazy
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{n,} n or more, greedy
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{n,}+ n or more, possessive
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{n,}? n or more, lazy
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</PRE>
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</P>
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<br><a name="SEC9" href="#TOC1">ANCHORS AND SIMPLE ASSERTIONS</a><br>
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<P>
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<pre>
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\b word boundary
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\B not a word boundary
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^ start of subject
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also after internal newline in multiline mode
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\A start of subject
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$ end of subject
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also before newline at end of subject
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also before internal newline in multiline mode
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\Z end of subject
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also before newline at end of subject
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\z end of subject
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\G first matching position in subject
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</PRE>
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</P>
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<br><a name="SEC10" href="#TOC1">MATCH POINT RESET</a><br>
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<P>
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<pre>
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\K reset start of match
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</PRE>
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</P>
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<br><a name="SEC11" href="#TOC1">ALTERNATION</a><br>
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<P>
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<pre>
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expr|expr|expr...
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</PRE>
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</P>
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<br><a name="SEC12" href="#TOC1">CAPTURING</a><br>
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<P>
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<pre>
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(...) capturing group
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(?<name>...) named capturing group (Perl)
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(?'name'...) named capturing group (Perl)
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(?P<name>...) named capturing group (Python)
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(?:...) non-capturing group
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(?|...) non-capturing group; reset group numbers for
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capturing groups in each alternative
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</PRE>
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</P>
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<br><a name="SEC13" href="#TOC1">ATOMIC GROUPS</a><br>
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<P>
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<pre>
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(?>...) atomic, non-capturing group
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</PRE>
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</P>
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<br><a name="SEC14" href="#TOC1">COMMENT</a><br>
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<P>
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<pre>
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(?#....) comment (not nestable)
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</PRE>
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</P>
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<br><a name="SEC15" href="#TOC1">OPTION SETTING</a><br>
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<P>
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<pre>
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(?i) caseless
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(?J) allow duplicate names
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(?m) multiline
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(?s) single line (dotall)
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(?U) default ungreedy (lazy)
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(?x) extended (ignore white space)
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(?-...) unset option(s)
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</PRE>
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</P>
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<br><a name="SEC16" href="#TOC1">LOOKAHEAD AND LOOKBEHIND ASSERTIONS</a><br>
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<P>
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<pre>
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(?=...) positive look ahead
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(?!...) negative look ahead
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(?<=...) positive look behind
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(?<!...) negative look behind
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</pre>
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Each top-level branch of a look behind must be of a fixed length.
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</P>
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<br><a name="SEC17" href="#TOC1">BACKREFERENCES</a><br>
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<P>
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<pre>
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\n reference by number (can be ambiguous)
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\gn reference by number
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\g{n} reference by number
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\g{-n} relative reference by number
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\k<name> reference by name (Perl)
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\k'name' reference by name (Perl)
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\g{name} reference by name (Perl)
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\k{name} reference by name (.NET)
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(?P=name) reference by name (Python)
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</PRE>
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</P>
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<br><a name="SEC18" href="#TOC1">SUBROUTINE REFERENCES (POSSIBLY RECURSIVE)</a><br>
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| 352 |
<P>
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<pre>
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(?R) recurse whole pattern
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(?n) call subpattern by absolute number
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(?+n) call subpattern by relative number
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(?-n) call subpattern by relative number
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(?&name) call subpattern by name (Perl)
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(?P>name) call subpattern by name (Python)
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\g<name> call subpattern by name (Oniguruma)
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\g'name' call subpattern by name (Oniguruma)
|
| 362 |
\g<n> call subpattern by absolute number (Oniguruma)
|
| 363 |
\g'n' call subpattern by absolute number (Oniguruma)
|
| 364 |
\g<+n> call subpattern by relative number (PCRE extension)
|
| 365 |
\g'+n' call subpattern by relative number (PCRE extension)
|
| 366 |
\g<-n> call subpattern by relative number (PCRE extension)
|
| 367 |
\g'-n' call subpattern by relative number (PCRE extension)
|
| 368 |
</PRE>
|
| 369 |
</P>
|
| 370 |
<br><a name="SEC19" href="#TOC1">CONDITIONAL PATTERNS</a><br>
|
| 371 |
<P>
|
| 372 |
<pre>
|
| 373 |
(?(condition)yes-pattern)
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(?(condition)yes-pattern|no-pattern)
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| 375 |
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| 376 |
(?(n)... absolute reference condition
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| 377 |
(?(+n)... relative reference condition
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| 378 |
(?(-n)... relative reference condition
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| 379 |
(?(<name>)... named reference condition (Perl)
|
| 380 |
(?('name')... named reference condition (Perl)
|
| 381 |
(?(name)... named reference condition (PCRE)
|
| 382 |
(?(R)... overall recursion condition
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| 383 |
(?(Rn)... specific group recursion condition
|
| 384 |
(?(R&name)... specific recursion condition
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| 385 |
(?(DEFINE)... define subpattern for reference
|
| 386 |
(?(assert)... assertion condition
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| 387 |
</PRE>
|
| 388 |
</P>
|
| 389 |
<br><a name="SEC20" href="#TOC1">BACKTRACKING CONTROL</a><br>
|
| 390 |
<P>
|
| 391 |
The following act immediately they are reached:
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| 392 |
<pre>
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| 393 |
(*ACCEPT) force successful match
|
| 394 |
(*FAIL) force backtrack; synonym (*F)
|
| 395 |
</pre>
|
| 396 |
The following act only when a subsequent match failure causes a backtrack to
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reach them. They all force a match failure, but they differ in what happens
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afterwards. Those that advance the start-of-match point do so only if the
|
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pattern is not anchored.
|
| 400 |
<pre>
|
| 401 |
(*COMMIT) overall failure, no advance of starting point
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| 402 |
(*PRUNE) advance to next starting character
|
| 403 |
(*SKIP) advance start to current matching position
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| 404 |
(*THEN) local failure, backtrack to next alternation
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| 405 |
</PRE>
|
| 406 |
</P>
|
| 407 |
<br><a name="SEC21" href="#TOC1">NEWLINE CONVENTIONS</a><br>
|
| 408 |
<P>
|
| 409 |
These are recognized only at the very start of the pattern or after a
|
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(*BSR_...) option.
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| 411 |
<pre>
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| 412 |
(*CR)
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| 413 |
(*LF)
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| 414 |
(*CRLF)
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| 415 |
(*ANYCRLF)
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| 416 |
(*ANY)
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</PRE>
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| 418 |
</P>
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| 419 |
<br><a name="SEC22" href="#TOC1">WHAT \R MATCHES</a><br>
|
| 420 |
<P>
|
| 421 |
These are recognized only at the very start of the pattern or after a
|
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(*...) option that sets the newline convention.
|
| 423 |
<pre>
|
| 424 |
(*BSR_ANYCRLF)
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| 425 |
(*BSR_UNICODE)
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| 426 |
</PRE>
|
| 427 |
</P>
|
| 428 |
<br><a name="SEC23" href="#TOC1">CALLOUTS</a><br>
|
| 429 |
<P>
|
| 430 |
<pre>
|
| 431 |
(?C) callout
|
| 432 |
(?Cn) callout with data n
|
| 433 |
</PRE>
|
| 434 |
</P>
|
| 435 |
<br><a name="SEC24" href="#TOC1">SEE ALSO</a><br>
|
| 436 |
<P>
|
| 437 |
<b>pcrepattern</b>(3), <b>pcreapi</b>(3), <b>pcrecallout</b>(3),
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| 438 |
<b>pcrematching</b>(3), <b>pcre</b>(3).
|
| 439 |
</P>
|
| 440 |
<br><a name="SEC25" href="#TOC1">AUTHOR</a><br>
|
| 441 |
<P>
|
| 442 |
Philip Hazel
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| 443 |
<br>
|
| 444 |
University Computing Service
|
| 445 |
<br>
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| 446 |
Cambridge CB2 3QH, England.
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<br>
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</P>
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<br><a name="SEC26" href="#TOC1">REVISION</a><br>
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<P>
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Last updated: 09 April 2008
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<br>
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Copyright © 1997-2008 University of Cambridge.
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<br>
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<p>
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Return to the <a href="index.html">PCRE index page</a>.
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</p>
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