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+
+This page is part of the PCRE HTML documentation. It was generated automatically
+from the original man page. If there is any nonsense in it, please consult the
+man page, in case the conversion went wrong.
+
+
+The full syntax and semantics of the regular expressions that are supported by +PCRE are described in the +pcrepattern +documentation. This document contains just a quick-reference summary of the +syntax. +
++
+ \x where x is non-alphanumeric is a literal x + \Q...\E treat enclosed characters as literal ++ +
+
+ \a alarm, that is, the BEL character (hex 07)
+ \cx "control-x", where x is any character
+ \e escape (hex 1B)
+ \f formfeed (hex 0C)
+ \n newline (hex 0A)
+ \r carriage return (hex 0D)
+ \t tab (hex 09)
+ \ddd character with octal code ddd, or backreference
+ \xhh character with hex code hh
+ \x{hhh..} character with hex code hhh..
+
+
++
+ . any character except newline;
+ in dotall mode, any character whatsoever
+ \C one byte, even in UTF-8 mode (best avoided)
+ \d a decimal digit
+ \D a character that is not a decimal digit
+ \h a horizontal whitespace character
+ \H a character that is not a horizontal whitespace character
+ \p{xx} a character with the xx property
+ \P{xx} a character without the xx property
+ \R a newline sequence
+ \s a whitespace character
+ \S a character that is not a whitespace character
+ \v a vertical whitespace character
+ \V a character that is not a vertical whitespace character
+ \w a "word" character
+ \W a "non-word" character
+ \X an extended Unicode sequence
+
+In PCRE, \d, \D, \s, \S, \w, and \W recognize only ASCII characters.
+
++
+ C Other + Cc Control + Cf Format + Cn Unassigned + Co Private use + Cs Surrogate + + L Letter + Ll Lower case letter + Lm Modifier letter + Lo Other letter + Lt Title case letter + Lu Upper case letter + L& Ll, Lu, or Lt + + 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 ++ +
+Arabic, +Armenian, +Balinese, +Bengali, +Bopomofo, +Braille, +Buginese, +Buhid, +Canadian_Aboriginal, +Cherokee, +Common, +Coptic, +Cuneiform, +Cypriot, +Cyrillic, +Deseret, +Devanagari, +Ethiopic, +Georgian, +Glagolitic, +Gothic, +Greek, +Gujarati, +Gurmukhi, +Han, +Hangul, +Hanunoo, +Hebrew, +Hiragana, +Inherited, +Kannada, +Katakana, +Kharoshthi, +Khmer, +Lao, +Latin, +Limbu, +Linear_B, +Malayalam, +Mongolian, +Myanmar, +New_Tai_Lue, +Nko, +Ogham, +Old_Italic, +Old_Persian, +Oriya, +Osmanya, +Phags_Pa, +Phoenician, +Runic, +Shavian, +Sinhala, +Syloti_Nagri, +Syriac, +Tagalog, +Tagbanwa, +Tai_Le, +Tamil, +Telugu, +Thaana, +Thai, +Tibetan, +Tifinagh, +Ugaritic, +Yi. +
++
+ [...] positive character class + [^...] negative character class + [x-y] range (can be used for hex characters) + [[:xxx:]] positive POSIX named set + [[:^xxx:]] negative POSIX named set + + alnum alphanumeric + alpha alphabetic + ascii 0-127 + blank space or tab + cntrl control character + digit decimal digit + graph printing, excluding space + lower lower case letter + print printing, including space + punct printing, excluding alphanumeric + space whitespace + upper upper case letter + word same as \w + xdigit hexadecimal digit ++In PCRE, POSIX character set names recognize only ASCII characters. You can use +\Q...\E inside a character class. + +
+
+ ? 0 or 1, greedy
+ ?+ 0 or 1, possessive
+ ?? 0 or 1, lazy
+ * 0 or more, greedy
+ *+ 0 or more, possessive
+ *? 0 or more, lazy
+ + 1 or more, greedy
+ ++ 1 or more, possessive
+ +? 1 or more, lazy
+ {n} exactly n
+ {n,m} at least n, no more than m, greedy
+ {n,m}+ at least n, no more than m, possessive
+ {n,m}? at least n, no more than m, lazy
+ {n,} n or more, greedy
+ {n,}+ n or more, possessive
+ {n,}? n or more, lazy
+
+
++
+ \b word boundary + \B not a word boundary + ^ start of subject + also after internal newline in multiline mode + \A start of subject + $ end of subject + also before newline at end of subject + also before internal newline in multiline mode + \Z end of subject + also before newline at end of subject + \z end of subject + \G first matching position in subject ++ +
+
+ \K reset start of match ++ +
+
+ expr|expr|expr... ++ +
+
+ (...) capturing group + (?<name>...) named capturing group (Perl) + (?'name'...) named capturing group (Perl) + (?P<name>...) named capturing group (Python) + (?:...) non-capturing group + (?|...) non-capturing group; reset group numbers for + capturing groups in each alternative ++ +
+
+ (?>...) atomic, non-capturing group ++ +
+
+ (?#....) comment (not nestable) ++ +
+
+ (?i) caseless + (?J) allow duplicate names + (?m) multiline + (?s) single line (dotall) + (?U) default ungreedy (lazy) + (?x) extended (ignore white space) + (?-...) unset option(s) ++ +
+
+ (?=...) positive look ahead + (?!...) negative look ahead + (?<=...) positive look behind + (?<!...) negative look behind ++Each top-level branch of a look behind must be of a fixed length. + +
+
+ \n reference by number (can be ambiguous)
+ \gn reference by number
+ \g{n} reference by number
+ \g{-n} relative reference by number
+ \k<name> reference by name (Perl)
+ \k'name' reference by name (Perl)
+ \g{name} reference by name (Perl)
+ \k{name} reference by name (.NET)
+ (?P=name) reference by name (Python)
+
+
++
+ (?R) recurse whole pattern + (?n) call subpattern by absolute number + (?+n) call subpattern by relative number + (?-n) call subpattern by relative number + (?&name) call subpattern by name (Perl) + (?P>name) call subpattern by name (Python) + \g<name> call subpattern by name (Oniguruma) + \g'name' call subpattern by name (Oniguruma) + \g<n> call subpattern by absolute number (Oniguruma) + \g'n' call subpattern by absolute number (Oniguruma) + \g<+n> call subpattern by relative number (PCRE extension) + \g'+n' call subpattern by relative number (PCRE extension) + \g<-n> call subpattern by relative number (PCRE extension) + \g'-n' call subpattern by relative number (PCRE extension) ++ +
+
+ (?(condition)yes-pattern)
+ (?(condition)yes-pattern|no-pattern)
+
+ (?(n)... absolute reference condition
+ (?(+n)... relative reference condition
+ (?(-n)... relative reference condition
+ (?(<name>)... named reference condition (Perl)
+ (?('name')... named reference condition (Perl)
+ (?(name)... named reference condition (PCRE)
+ (?(R)... overall recursion condition
+ (?(Rn)... specific group recursion condition
+ (?(R&name)... specific recursion condition
+ (?(DEFINE)... define subpattern for reference
+ (?(assert)... assertion condition
+
+
++The following act immediately they are reached: +
+ (*ACCEPT) force successful match + (*FAIL) force backtrack; synonym (*F) ++The following act only when a subsequent match failure causes a backtrack to +reach them. They all force a match failure, but they differ in what happens +afterwards. Those that advance the start-of-match point do so only if the +pattern is not anchored. +
+ (*COMMIT) overall failure, no advance of starting point + (*PRUNE) advance to next starting character + (*SKIP) advance start to current matching position + (*THEN) local failure, backtrack to next alternation ++ +
+These are recognized only at the very start of the pattern or after a +(*BSR_...) option. +
+ (*CR) + (*LF) + (*CRLF) + (*ANYCRLF) + (*ANY) ++ +
+These are recognized only at the very start of the pattern or after a +(*...) option that sets the newline convention. +
+ (*BSR_ANYCRLF) + (*BSR_UNICODE) ++ +
+
+ (?C) callout + (?Cn) callout with data n ++ +
+pcrepattern(3), pcreapi(3), pcrecallout(3), +pcrematching(3), pcre(3). +
+
+Philip Hazel
+
+University Computing Service
+
+Cambridge CB2 3QH, England.
+
+
+Last updated: 09 April 2008
+
+Copyright © 1997-2008 University of Cambridge.
+
+
+Return to the PCRE index page. +