.\" Automatically generated by Pod::Man v1.37, Pod::Parser v1.32 .\" .\" Standard preamble: .\" ======================================================================== .de Sh \" Subsection heading .br .if t .Sp .ne 5 .PP \fB\\$1\fR .PP .. .de Sp \" Vertical space (when we can't use .PP) .if t .sp .5v .if n .sp .. .de Vb \" Begin verbatim text .ft CW .nf .ne \\$1 .. .de Ve \" End verbatim text .ft R .fi .. .\" Set up some character translations and predefined strings. \*(-- will .\" give an unbreakable dash, \*(PI will give pi, \*(L" will give a left .\" double quote, and \*(R" will give a right double quote. | will give a .\" real vertical bar. \*(C+ will give a nicer C++. Capital omega is used to .\" do unbreakable dashes and therefore won't be available. \*(C` and \*(C' .\" expand to `' in nroff, nothing in troff, for use with C<>. .tr \(*W-|\(bv\*(Tr .ds C+ C\v'-.1v'\h'-1p'\s-2+\h'-1p'+\s0\v'.1v'\h'-1p' .ie n \{\ . ds -- \(*W- . ds PI pi . if (\n(.H=4u)&(1m=24u) .ds -- \(*W\h'-12u'\(*W\h'-12u'-\" diablo 10 pitch . if (\n(.H=4u)&(1m=20u) .ds -- \(*W\h'-12u'\(*W\h'-8u'-\" diablo 12 pitch . ds L" "" . ds R" "" . ds C` "" . ds C' "" 'br\} .el\{\ . ds -- \|\(em\| . ds PI \(*p . ds L" `` . ds R" '' 'br\} .\" .\" If the F register is turned on, we'll generate index entries on stderr for .\" titles (.TH), headers (.SH), subsections (.Sh), items (.Ip), and index .\" entries marked with X<> in POD. Of course, you'll have to process the .\" output yourself in some meaningful fashion. .if \nF \{\ . de IX . tm Index:\\$1\t\\n%\t"\\$2" .. . nr % 0 . rr F .\} .\" .\" For nroff, turn off justification. 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No user-serviceable parts. . \" fudge factors for nroff and troff .if n \{\ . ds #H 0 . ds #V .8m . ds #F .3m . ds #[ \f1 . ds #] \fP .\} .if t \{\ . ds #H ((1u-(\\\\n(.fu%2u))*.13m) . ds #V .6m . ds #F 0 . ds #[ \& . ds #] \& .\} . \" simple accents for nroff and troff .if n \{\ . ds ' \& . ds ` \& . ds ^ \& . ds , \& . ds ~ ~ . ds / .\} .if t \{\ . ds ' \\k:\h'-(\\n(.wu*8/10-\*(#H)'\'\h"|\\n:u" . ds ` \\k:\h'-(\\n(.wu*8/10-\*(#H)'\`\h'|\\n:u' . ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'^\h'|\\n:u' . ds , \\k:\h'-(\\n(.wu*8/10)',\h'|\\n:u' . ds ~ \\k:\h'-(\\n(.wu-\*(#H-.1m)'~\h'|\\n:u' . ds / \\k:\h'-(\\n(.wu*8/10-\*(#H)'\z\(sl\h'|\\n:u' .\} . \" troff and (daisy-wheel) nroff accents .ds : \\k:\h'-(\\n(.wu*8/10-\*(#H+.1m+\*(#F)'\v'-\*(#V'\z.\h'.2m+\*(#F'.\h'|\\n:u'\v'\*(#V' .ds 8 \h'\*(#H'\(*b\h'-\*(#H' .ds o \\k:\h'-(\\n(.wu+\w'\(de'u-\*(#H)/2u'\v'-.3n'\*(#[\z\(de\v'.3n'\h'|\\n:u'\*(#] .ds d- \h'\*(#H'\(pd\h'-\w'~'u'\v'-.25m'\f2\(hy\fP\v'.25m'\h'-\*(#H' .ds D- D\\k:\h'-\w'D'u'\v'-.11m'\z\(hy\v'.11m'\h'|\\n:u' .ds th \*(#[\v'.3m'\s+1I\s-1\v'-.3m'\h'-(\w'I'u*2/3)'\s-1o\s+1\*(#] .ds Th \*(#[\s+2I\s-2\h'-\w'I'u*3/5'\v'-.3m'o\v'.3m'\*(#] .ds ae a\h'-(\w'a'u*4/10)'e .ds Ae A\h'-(\w'A'u*4/10)'E . \" corrections for vroff .if v .ds ~ \\k:\h'-(\\n(.wu*9/10-\*(#H)'\s-2\u~\d\s+2\h'|\\n:u' .if v .ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'\v'-.4m'^\v'.4m'\h'|\\n:u' . \" for low resolution devices (crt and lpr) .if \n(.H>23 .if \n(.V>19 \ \{\ . ds : e . ds 8 ss . ds o a . ds d- d\h'-1'\(ga . ds D- D\h'-1'\(hy . ds th \o'bp' . ds Th \o'LP' . ds ae ae . ds Ae AE .\} .rm #[ #] #H #V #F C .\" ======================================================================== .\" .IX Title "PERLREREF 1" .TH PERLREREF 1 "2006-01-07" "perl v5.8.8" "Perl Programmers Reference Guide" .SH "NAME" perlreref \- Perl Regular Expressions Reference .SH "DESCRIPTION" .IX Header "DESCRIPTION" This is a quick reference to Perl's regular expressions. For full information see perlre and perlop, as well as the \*(L"\s-1SEE\s0 \s-1ALSO\s0\*(R" section in this document. .Sh "\s-1OPERATORS\s0" .IX Subsection "OPERATORS" .Vb 2 \& =~ determines to which variable the regex is applied. \& In its absence, $_ is used. .Ve .PP .Vb 1 \& $var =~ /foo/; .Ve .PP .Vb 3 \& !~ determines to which variable the regex is applied, \& and negates the result of the match; it returns \& false if the match succeeds, and true if it fails. .Ve .PP .Vb 1 \& $var !~ /foo/; .Ve .PP .Vb 2 \& m/pattern/igmsoxc searches a string for a pattern match, \& applying the given options. .Ve .PP .Vb 7 \& i case-Insensitive \& g Global - all occurrences \& m Multiline mode - ^ and $ match internal lines \& s match as a Single line - . matches \en \& o compile pattern Once \& x eXtended legibility - free whitespace and comments \& c don't reset pos on failed matches when using /g .Ve .PP .Vb 3 \& If 'pattern' is an empty string, the last I matched \& regex is used. Delimiters other than '/' may be used for both this \& operator and the following ones. .Ve .PP .Vb 3 \& qr/pattern/imsox lets you store a regex in a variable, \& or pass one around. Modifiers as for m// and are stored \& within the regex. .Ve .PP .Vb 3 \& s/pattern/replacement/igmsoxe substitutes matches of \& 'pattern' with 'replacement'. Modifiers as for m// \& with one addition: .Ve .PP .Vb 1 \& e Evaluate replacement as an expression .Ve .PP .Vb 2 \& 'e' may be specified multiple times. 'replacement' is interpreted \& as a double quoted string unless a single-quote (') is the delimiter. .Ve .PP .Vb 2 \& ?pattern? is like m/pattern/ but matches only once. No alternate \& delimiters can be used. Must be reset with L. .Ve .Sh "\s-1SYNTAX\s0" .IX Subsection "SYNTAX" .Vb 13 \& \e Escapes the character immediately following it \& . Matches any single character except a newline (unless /s is used) \& ^ Matches at the beginning of the string (or line, if /m is used) \& $ Matches at the end of the string (or line, if /m is used) \& * Matches the preceding element 0 or more times \& + Matches the preceding element 1 or more times \& ? Matches the preceding element 0 or 1 times \& {...} Specifies a range of occurrences for the element preceding it \& [...] Matches any one of the characters contained within the brackets \& (...) Groups subexpressions for capturing to $1, $2... \& (?:...) Groups subexpressions without capturing (cluster) \& | Matches either the subexpression preceding or following it \& \e1, \e2 ... The text from the Nth group .Ve .Sh "\s-1ESCAPE\s0 \s-1SEQUENCES\s0" .IX Subsection "ESCAPE SEQUENCES" These work as in normal strings. .PP .Vb 11 \& \ea Alarm (beep) \& \ee Escape \& \ef Formfeed \& \en Newline \& \er Carriage return \& \et Tab \& \e037 Any octal ASCII value \& \ex7f Any hexadecimal ASCII value \& \ex{263a} A wide hexadecimal value \& \ecx Control-x \& \eN{name} A named character .Ve .PP .Vb 6 \& \el Lowercase next character \& \eu Titlecase next character \& \eL Lowercase until \eE \& \eU Uppercase until \eE \& \eQ Disable pattern metacharacters until \eE \& \eE End case modification .Ve .PP For Titlecase, see \*(L"Titlecase\*(R". .PP This one works differently from normal strings: .PP .Vb 1 \& \eb An assertion, not backspace, except in a character class .Ve .Sh "\s-1CHARACTER\s0 \s-1CLASSES\s0" .IX Subsection "CHARACTER CLASSES" .Vb 4 \& [amy] Match 'a', 'm' or 'y' \& [f-j] Dash specifies "range" \& [f-j-] Dash escaped or at start or end means 'dash' \& [^f-j] Caret indicates "match any character _except_ these" .Ve .PP The following sequences work within or without a character class. The first six are locale aware, all are Unicode aware. The default character class equivalent are given. See perllocale and perlunicode for details. .PP .Vb 6 \& \ed A digit [0-9] \& \eD A nondigit [^0-9] \& \ew A word character [a-zA-Z0-9_] \& \eW A non-word character [^a-zA-Z0-9_] \& \es A whitespace character [ \et\en\er\ef] \& \eS A non-whitespace character [^ \et\en\er\ef] .Ve .PP .Vb 6 \& \eC Match a byte (with Unicode, '.' matches a character) \& \epP Match P-named (Unicode) property \& \ep{...} Match Unicode property with long name \& \ePP Match non-P \& \eP{...} Match lack of Unicode property with long name \& \eX Match extended unicode sequence .Ve .PP \&\s-1POSIX\s0 character classes and their Unicode and Perl equivalents: .PP .Vb 15 \& alnum IsAlnum Alphanumeric \& alpha IsAlpha Alphabetic \& ascii IsASCII Any ASCII char \& blank IsSpace [ \et] Horizontal whitespace (GNU extension) \& cntrl IsCntrl Control characters \& digit IsDigit \ed Digits \& graph IsGraph Alphanumeric and punctuation \& lower IsLower Lowercase chars (locale and Unicode aware) \& print IsPrint Alphanumeric, punct, and space \& punct IsPunct Punctuation \& space IsSpace [\es\eck] Whitespace \& IsSpacePerl \es Perl's whitespace definition \& upper IsUpper Uppercase chars (locale and Unicode aware) \& word IsWord \ew Alphanumeric plus _ (Perl extension) \& xdigit IsXDigit [0-9A-Fa-f] Hexadecimal digit .Ve .PP Within a character class: .PP .Vb 3 \& POSIX traditional Unicode \& [:digit:] \ed \ep{IsDigit} \& [:^digit:] \eD \eP{IsDigit} .Ve .Sh "\s-1ANCHORS\s0" .IX Subsection "ANCHORS" All are zero-width assertions. .PP .Vb 8 \& ^ Match string start (or line, if /m is used) \& $ Match string end (or line, if /m is used) or before newline \& \eb Match word boundary (between \ew and \eW) \& \eB Match except at word boundary (between \ew and \ew or \eW and \eW) \& \eA Match string start (regardless of /m) \& \eZ Match string end (before optional newline) \& \ez Match absolute string end \& \eG Match where previous m//g left off .Ve .Sh "\s-1QUANTIFIERS\s0" .IX Subsection "QUANTIFIERS" Quantifiers are greedy by default \*(-- match the \fBlongest\fR leftmost. .PP .Vb 8 \& Maximal Minimal Allowed range \& ------- ------- ------------- \& {n,m} {n,m}? Must occur at least n times but no more than m times \& {n,} {n,}? Must occur at least n times \& {n} {n}? Must occur exactly n times \& * *? 0 or more times (same as {0,}) \& + +? 1 or more times (same as {1,}) \& ? ?? 0 or 1 time (same as {0,1}) .Ve .PP There is no quantifier {,n} \*(-- that gets understood as a literal string. .Sh "\s-1EXTENDED\s0 \s-1CONSTRUCTS\s0" .IX Subsection "EXTENDED CONSTRUCTS" .Vb 11 \& (?#text) A comment \& (?imxs-imsx:...) Enable/disable option (as per m// modifiers) \& (?=...) Zero-width positive lookahead assertion \& (?!...) Zero-width negative lookahead assertion \& (?<=...) Zero-width positive lookbehind assertion \& (?...) Grab what we can, prohibit backtracking \& (?{ code }) Embedded code, return value becomes $^R \& (??{ code }) Dynamic regex, return value used as regex \& (?(cond)yes|no) cond being integer corresponding to capturing parens \& (?(cond)yes) or a lookaround/eval zero-width assertion .Ve .Sh "\s-1VARIABLES\s0" .IX Subsection "VARIABLES" .Vb 2 \& $_ Default variable for operators to use \& $* Enable multiline matching (deprecated; not in 5.9.0 or later) .Ve .PP .Vb 3 \& $& Entire matched string \& $` Everything prior to matched string \& $' Everything after to matched string .Ve .PP The use of those last three will slow down \fBall\fR regex use within your program. Consult perlvar for \f(CW@LAST_MATCH_START\fR to see equivalent expressions that won't cause slow down. See also Devel::SawAmpersand. .PP .Vb 6 \& $1, $2 ... hold the Xth captured expr \& $+ Last parenthesized pattern match \& $^N Holds the most recently closed capture \& $^R Holds the result of the last (?{...}) expr \& @- Offsets of starts of groups. $-[0] holds start of whole match \& @+ Offsets of ends of groups. $+[0] holds end of whole match .Ve .PP Captured groups are numbered according to their \fIopening\fR paren. .Sh "\s-1FUNCTIONS\s0" .IX Subsection "FUNCTIONS" .Vb 4 \& lc Lowercase a string \& lcfirst Lowercase first char of a string \& uc Uppercase a string \& ucfirst Titlecase first char of a string .Ve .PP .Vb 4 \& pos Return or set current match position \& quotemeta Quote metacharacters \& reset Reset ?pattern? status \& study Analyze string for optimizing matching .Ve .PP .Vb 1 \& split Use regex to split a string into parts .Ve .PP The first four of these are like the escape sequences \f(CW\*(C`\eL\*(C'\fR, \f(CW\*(C`\el\*(C'\fR, \&\f(CW\*(C`\eU\*(C'\fR, and \f(CW\*(C`\eu\*(C'\fR. For Titlecase, see \*(L"Titlecase\*(R". .Sh "\s-1TERMINOLOGY\s0" .IX Subsection "TERMINOLOGY" \fITitlecase\fR .IX Subsection "Titlecase" .PP Unicode concept which most often is equal to uppercase, but for certain characters like the German \*(L"sharp s\*(R" there is a difference. .SH "AUTHOR" .IX Header "AUTHOR" Iain Truskett. .PP This document may be distributed under the same terms as Perl itself. .SH "SEE ALSO" .IX Header "SEE ALSO" .IP "\(bu" 4 perlretut for a tutorial on regular expressions. .IP "\(bu" 4 perlrequick for a rapid tutorial. .IP "\(bu" 4 perlre for more details. .IP "\(bu" 4 perlvar for details on the variables. .IP "\(bu" 4 perlop for details on the operators. .IP "\(bu" 4 perlfunc for details on the functions. .IP "\(bu" 4 perlfaq6 for FAQs on regular expressions. .IP "\(bu" 4 The re module to alter behaviour and aid debugging. .IP "\(bu" 4 \&\*(L"Debugging regular expressions\*(R" in perldebug .IP "\(bu" 4 perluniintro, perlunicode, charnames and locale for details on regexes and internationalisation. .IP "\(bu" 4 \&\fIMastering Regular Expressions\fR by Jeffrey Friedl (\fIhttp://regex.info/\fR) for a thorough grounding and reference on the topic. .SH "THANKS" .IX Header "THANKS" David P.C. Wollmann, Richard Soderberg, Sean M. Burke, Tom Christiansen, Jim Cromie, and Jeffrey Goff for useful advice.