perlreref - Perl 正規表示式參考
這是 Perl 正規表示式的快速參考。如需完整資訊，請參閱 perlre 和 perlop，以及此文件中的 "另請參閱" 部分。
=~ 決定正規表示式套用至哪個變數。若沒有，則使用 $_。
$var =~ /foo/;!~ 決定正規表示式套用至哪個變數，並否定配對的結果；如果配對成功，則傳回 false，如果失敗，則傳回 true。
$var !~ /foo/;m/pattern/msixpogcdualn 在字串中搜尋模式配對，並套用指定的選項。
m Multiline mode - ^ and $ match internal lines
s match as a Single line - . matches \n
i case-Insensitive
x eXtended legibility - free whitespace and comments
p Preserve a copy of the matched string -
${^PREMATCH}, ${^MATCH}, ${^POSTMATCH} will be defined.
o compile pattern Once
g Global - all occurrences
c don't reset pos on failed matches when using /g
a restrict \d, \s, \w and [:posix:] to match ASCII only
aa (two a's) also /i matches exclude ASCII/non-ASCII
l match according to current locale
u match according to Unicode rules
d match according to native rules unless something indicates
Unicode
n Non-capture mode. Don't let () fill in $1, $2, etc...如果 'pattern' 為空字串，則使用最後一次成功配對的正規表示式。此運算子與後面的運算子都可以使用 '/' 以外的分隔符號。如果分隔符號為 '/'，則可以省略開頭的 m。
qr/pattern/msixpodualn 讓你可以將正規表示式儲存在變數中，或傳遞一個正規表示式。修改器如同 m//，並儲存在正規表示式中。
s/pattern/replacement/msixpogcedual 用 'replacement' 取代 'pattern' 的比對結果。修改器如同 m//，並新增兩個
e Evaluate 'replacement' as an expression
r Return substitution and leave the original string untouched.'e' 可以指定多次。'replacement' 被解釋為雙引號字串，除非分隔符號為單引號 (')。
m?pattern? 類似於 m/pattern/ 但只比對一次。無法使用其他分隔符號。必須使用 reset() 重設。
\ 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
\g1 or \g{1}, \g2 ... Matches the text from the Nth group
\1, \2, \3 ... Matches the text from the Nth group
\g-1 or \g{-1}, \g-2 ... Matches the text from the Nth previous group
\g{name} Named backreference
\k<name> Named backreference
\k'name' Named backreference
(?P=name) Named backreference (python syntax)這些序列與一般字串中的相同。
\a Alarm (beep)
\e Escape
\f Formfeed
\n Newline
\r Carriage return
\t Tab
\037 Char whose ordinal is the 3 octal digits, max \777
\o{2307} Char whose ordinal is the octal number, unrestricted
\x7f Char whose ordinal is the 2 hex digits, max \xFF
\x{263a} Char whose ordinal is the hex number, unrestricted
\cx Control-x
\N{name} A named Unicode character or character sequence
\N{U+263D} A Unicode character by hex ordinal
\l Lowercase next character
\u Titlecase next character
\L Lowercase until \E
\U Uppercase until \E
\F Foldcase until \E
\Q Disable pattern metacharacters until \E
\E End modification有關標題大小寫，請參閱 "標題大小寫"。
這個序列與一般字串中的不同
\b An assertion, not backspace, except in a character class[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"以下序列 (\N 除外) 可在字元類別內或外使用。前六個會依據區域設定，全部都支援 Unicode。有關詳細資訊，請參閱 perllocale 和 perlunicode。
\d A digit
\D A nondigit
\w A word character
\W A non-word character
\s A whitespace character
\S A non-whitespace character
\h A horizontal whitespace
\H A non horizontal whitespace
\N A non newline (when not followed by '{NAME}';;
not valid in a character class; equivalent to [^\n]; it's
like '.' without /s modifier)
\v A vertical whitespace
\V A non vertical whitespace
\R A generic newline (?>\v|\x0D\x0A)
\pP Match P-named (Unicode) property
\p{...} Match Unicode property with name longer than 1 character
\PP Match non-P
\P{...} Match lack of Unicode property with name longer than 1 char
\X Match Unicode extended grapheme clusterPOSIX 字元類別及其 Unicode 和 Perl 等效字元
ASCII- Full-
POSIX range range backslash
[[:...:]] \p{...} \p{...} sequence Description
-----------------------------------------------------------------------
alnum PosixAlnum XPosixAlnum 'alpha' plus 'digit'
alpha PosixAlpha XPosixAlpha Alphabetic characters
ascii ASCII Any ASCII character
blank PosixBlank XPosixBlank \h Horizontal whitespace;
full-range also
written as
\p{HorizSpace} (GNU
extension)
cntrl PosixCntrl XPosixCntrl Control characters
digit PosixDigit XPosixDigit \d Decimal digits
graph PosixGraph XPosixGraph 'alnum' plus 'punct'
lower PosixLower XPosixLower Lowercase characters
print PosixPrint XPosixPrint 'graph' plus 'space',
but not any Controls
punct PosixPunct XPosixPunct Punctuation and Symbols
in ASCII-range; just
punct outside it
space PosixSpace XPosixSpace \s Whitespace
upper PosixUpper XPosixUpper Uppercase characters
word PosixWord XPosixWord \w 'alnum' + Unicode marks
+ connectors, like
'_' (Perl extension)
xdigit ASCII_Hex_Digit XPosixDigit Hexadecimal digit,
ASCII-range is
[0-9A-Fa-f]此外，還有各種同義詞，例如 \p{Alpha} 表示 \p{XPosixAlpha}；全部列於 "perluniprops 中可透過 \p{} 和 \P{} 存取的屬性"
在字元類別內
POSIX traditional Unicode
[:digit:] \d \p{Digit}
[:^digit:] \D \P{Digit}全部都是零寬度斷言。
^ Match string start (or line, if /m is used)
$ Match string end (or line, if /m is used) or before newline
\b{} Match boundary of type specified within the braces
\B{} Match wherever \b{} doesn't match
\b Match word boundary (between \w and \W)
\B Match except at word boundary (between \w and \w or \W and \W)
\A Match string start (regardless of /m)
\Z Match string end (before optional newline)
\z Match absolute string end
\G Match where previous m//g left off
\K Keep the stuff left of the \K, don't include it in $&量詞預設為貪婪，並比對最長的左端。
Maximal Minimal Possessive Allowed range
------- ------- ---------- -------------
{n,m} {n,m}? {n,m}+ Must occur at least n times
but no more than m times
{n,} {n,}? {n,}+ Must occur at least n times
{,n} {,n}? {,n}+ Must occur at most n times
{n} {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})佔有形式 (Perl 5.10 中的新增功能) 可防止回溯：由具有佔有量詞的模式比對到的內容不會被回溯，即使這會導致整個比對失敗。
(?#text) A comment
(?:...) Groups subexpressions without capturing (cluster)
(?pimsx-imsx:...) Enable/disable option (as per m// modifiers)
(?=...) Zero-width positive lookahead assertion
(*pla:...) Same, starting in 5.32; experimentally in 5.28
(*positive_lookahead:...) Same, same versions as *pla
(?!...) Zero-width negative lookahead assertion
(*nla:...) Same, starting in 5.32; experimentally in 5.28
(*negative_lookahead:...) Same, same versions as *nla
(?<=...) Zero-width positive lookbehind assertion
(*plb:...) Same, starting in 5.32; experimentally in 5.28
(*positive_lookbehind:...) Same, same versions as *plb
(?<!...) Zero-width negative lookbehind assertion
(*nlb:...) Same, starting in 5.32; experimentally in 5.28
(*negative_lookbehind:...) Same, same versions as *plb
(?>...) Grab what we can, prohibit backtracking
(*atomic:...) Same, starting in 5.32; experimentally in 5.28
(?|...) Branch reset
(?<name>...) Named capture
(?'name'...) Named capture
(?P<name>...) Named capture (python syntax)
(?[...]) Extended bracketed character class
(?{ code }) Embedded code, return value becomes $^R
(??{ code }) Dynamic regex, return value used as regex
(?N) Recurse into subpattern number N
(?-N), (?+N) Recurse into Nth previous/next subpattern
(?R), (?0) Recurse at the beginning of the whole pattern
(?&name) Recurse into a named subpattern
(?P>name) Recurse into a named subpattern (python syntax)
(?(cond)yes|no)
(?(cond)yes) Conditional expression, where "(cond)" can be:
(?=pat) lookahead; also (*pla:pat)
(*positive_lookahead:pat)
(?!pat) negative lookahead; also (*nla:pat)
(*negative_lookahead:pat)
(?<=pat) lookbehind; also (*plb:pat)
(*lookbehind:pat)
(?<!pat) negative lookbehind; also (*nlb:pat)
(*negative_lookbehind:pat)
(N) subpattern N has matched something
(<name>) named subpattern has matched something
('name') named subpattern has matched something
(?{code}) code condition
(R) true if recursing
(RN) true if recursing into Nth subpattern
(R&name) true if recursing into named subpattern
(DEFINE) always false, no no-pattern allowed$_ Default variable for operators to use
$` Everything prior to matched string
$& Entire matched string
$' Everything after to matched string
${^PREMATCH} Everything prior to matched string
${^MATCH} Entire matched string
${^POSTMATCH} Everything after to matched string對於仍使用 Perl 5.18 或更早版本的人員，請注意：使用 $`、$& 或 $' 會減慢程式中所有正規表示式的使用速度。請參閱 perlvar 中的 @-，以查看不會導致速度變慢的等效表達式。另請參閱 Devel::SawAmpersand。從 Perl 5.10 開始，你也可以使用等效變數 ${^PREMATCH}、${^MATCH} 和 ${^POSTMATCH}，但要讓它們被定義，你必須在正規表示式中指定 /p (保留) 修改器。在 Perl 5.20 中，使用 $`、$& 和 $' 沒有速度差異。
$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
%+ Named capture groups
%- Named capture groups, as array refs擷取的群組會根據其開啟括號進行編號。
lc Lowercase a string
lcfirst Lowercase first char of a string
uc Uppercase a string
ucfirst Titlecase first char of a string
fc Foldcase a string
pos Return or set current match position
quotemeta Quote metacharacters
reset Reset m?pattern? status
study Analyze string for optimizing matching
split Use a regex to split a string into parts這前五個函式類似於跳脫序列 \L、\l、\U、\u 和 \F。有關標題大小寫，請參閱 "標題大小寫"；有關摺疊大小寫，請參閱 "摺疊大小寫"。
Unicode 概念通常等於大寫，但對於某些字元，例如德語的「銳 s」，則有所不同。
Unicode 形式，在比較字串時很有用，不論大小寫，因為某些字元具有複雜的一對多大小寫對應。主要是小寫的變體。
Iain Truskett。由 Perl 5 Porters 更新。
此文件可以與 Perl 本身相同的條款散布。
perlretut，以取得正規表示式的教學課程。
perlrequick，以取得快速教學課程。
perlre，以取得更多詳細資訊。
perlvar，以取得變數的詳細資訊。
perlop，以取得運算子的詳細資訊。
perlfunc，以取得函數的詳細資訊。
perlfaq6，以取得正規表示式的常見問題集。
perlrebackslash，以取得反斜線序列的參考。
perlrecharclass，以取得字元類別的參考。
re 模組，用於變更行為並協助除錯。
perluniintro、perlunicode、charnames 和 perllocale，以取得正規表示式和國際化的詳細資訊。
Jeffrey Friedl 所著的《Mastering Regular Expressions》(http://oreilly.com/catalog/9780596528126/)，以取得關於此主題的深入基礎和參考。
David P.C. Wollmann、Richard Soderberg、Sean M. Burke、Tom Christiansen、Jim Cromie 和 Jeffrey Goff 提供有用的建議。