Regex Cheat Sheet

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6 min read

Reference

  • Regex Cheat Sheet - Cheat Sheet Maker

    Other Syntax

    SyntaxLegendExampleSample Match
    \KKeep Out
    Perl, PCRE (C, PHP, R…), Python's alternate regex engine, Ruby 2+: drop everything that was matched so far from the overall match to be returned
    prefix\K\d+12
    \Q…\EPerl, PCRE (C, PHP, R…), Java: treat anything between the delimiters as a literal string. Useful to escape metacharacters.\Q(C++ ?)\E(C++ ?)
    ### Character Class Operations
    Class OperationLegendExampleSample Match
    […-[…]].NET: character class subtraction. One character that is in those on the left, but not in the subtracted class.[a-z-[aeiou]]Any lowercase consonant
    […-[…]].NET: character class subtraction.[\p{IsArabic}-[\D]]An Arabic character that is not a non-digit, i.e., an Arabic digit
    […&&[…]]Java, Ruby 2+: character class intersection. One character that is both in those on the left and in the && class.[\S&&[\D]]An non-whitespace character that is a non-digit.
    […&&[…]]Java, Ruby 2+: character class intersection.[\S&&[\D]&&[^a-zA-Z]]An non-whitespace character that a non-digit and not a letter.
    […&&[^…]]Java, Ruby 2+: character class subtraction is obtained by intersecting a class with a negated class[a-z&&[^aeiou]]An English lowercase letter that is not a vowel.
    […&&[^…]]Java, Ruby 2+: character class subtraction[\p{InArabic}&&[^\p{L}\p{N}]]An Arabic character that is not a letter or a number
    ### Lookarounds
    LookaroundLegendExampleSample Match
    (?=…)Positive lookahead(?=\d{10})\d{5}01234 in 0123456789
    (?<=…)Positive lookbehind(?<=\d)catcat in 1cat
    (?!…)Negative lookahead(?!theatre)the\w+theme
    (?<!…)Negative lookbehind\w{3}(?<!mon)sterMunster
    ### Inline Modifiers
    ModifierLegendExampleSample Match
    (?i)Case-insensitive mode
    (except JavaScript)
    (?i)MondaymonDAY
    (?s)DOTALL mode (except JS and Ruby). The dot (.) matches new line characters (\r\n). Also known as "single-line mode" because the dot treats the entire input as a single line(?s)From A.to ZFrom A
    to Z
    (?m)Multiline mode
    (except Ruby and JS) ^ and $ match at the beginning and end of every line
    (?m)1\r\n^2$\r\n^3$1
    2
    3
    (?m)In Ruby: the same as (?s) in other engines, i.e. DOTALL mode, i.e. dot matches line breaks(?m)From A.to ZFrom A
    to Z
    (?x)Free-Spacing Mode mode
    (except JavaScript). Also known as comment mode or whitespace mode
    (?x) # this is a
    # comment
    abc # write on multiple
    # lines
    [ ]d # spaces must be
    # in brackets
    abc d
    (?n).NET, PCRE 10.30+: named capture onlyTurns all (parentheses) into non-capture groups. To capture, use named groups.
    (?d)Java: Unix linebreaks onlyThe dot and the ^ and $ anchors are only affected by \n
    (?^)PCRE 10.32+: unset modifiersUnsets ismnx modifiers
    ### POSIX Classes
    CharacterLegendExampleSample Match
    [:alpha:]PCRE (C, PHP, R…): ASCII letters A-Z and a-z[8[:alpha:]]+WellDone88
    [:alpha:]Ruby 2: Unicode letter or ideogram[[:alpha:]\d]+кошка99
    [:alnum:]PCRE (C, PHP, R…): ASCII digits and letters A-Z and a-z[[:alnum:]]{10}ABCDE12345
    [:alnum:]Ruby 2: Unicode digit, letter or ideogram[[:alnum:]]{10}кошка90210
    [:punct:]PCRE (C, PHP, R…): ASCII punctuation mark[[:punct:]]+?!.,:;
    [:punct:]Ruby: Unicode punctuation mark[[:punct:]]+‽,:〽⁆
    ### Anchors and Boundaries
    AnchorLegendExampleSample Match
    ^Start of string or start of line depending on multiline mode. (But when [^inside brackets], it means "not")^abc .abc (line start)
    $End of string or end of line depending on multiline mode. Many engine-dependent subtleties..? the end$this is the end
    \ABeginning of string
    (all major engines except JS)
    \Aabc[\d\D]abc (string...
    ...start)
    \zVery end of the string
    Not available in Python and JS
    the end\zthis is...\n...the end
    \ZEnd of string or (except Python) before final line break
    Not available in JS
    the end\Zthis is...\n...the end\n
    \GBeginning of String or End of Previous Match
    .NET, Java, PCRE (C, PHP, R…), Perl, Ruby
    \bWord boundary
    Most engines: position where one side only is an ASCII letter, digit or underscore
    Bob.\bcat\bBob ate the cat
    \bWord boundary
    .NET, Java, Python 3, Ruby: position where one side only is a Unicode letter, digit or underscore
    Bob.\b\кошка\bBob ate the кошка
    \BNot a word boundaryc.\Bcat\B.copycats
    ### Character Classes
    CharacterLegendExampleSample Match
    [ … ]One of the characters in the brackets[AEIOU]One uppercase vowel
    [ … ]One of the characters in the bracketsT[ao]pTap or Top
    -Range indicator[a-z]One lowercase letter
    [x-y]One of the characters in the range from x to y[A-Z]+GREAT
    [ … ]One of the characters in the brackets[AB1-5w-z]One of either: A,B,1,2,3,4,5,w,x,y,z
    [x-y]One of the characters in the range from x to y[ -~]+Characters in the printable section of the ASCII table.
    [^x]One character that is not x[^a-z]{3}A1!
    [^x-y]One of the characters not in the range from x to y[^ -~]+Characters that are not in the printable section of the ASCII table.
    [\d\D]One character that is a digit or a non-digit[\d\D]+Any characters, inc-
    luding new lines, which the regular dot doesn't match
    [\x41]Matches the character at hexadecimal position 41 in the ASCII table, i.e. A[\x41-\x45]{3}ABE
    ### More Quantifiers
    QuantifierLegendExampleSample Match
    +The + (one or more) is "greedy"\d+12345
    ?Makes quantifiers "lazy"\d+?1 in 12345
    The (zero or more) is "greedy"AAAA
    ?Makes quantifiers "lazy"A?empty in AAA
    {2,4}Two to four times, "greedy"\w{2,4}abcd
    ?Makes quantifiers "lazy"\w{2,4}?ab in abcd
    ### More White-Space
    CharacterLegendExampleSample Match
    \tTabT\t\w{2}T     ab
    \rCarriage return charactersee below
    \nLine feed charactersee below
    \r\nLine separator on WindowsAB\r\nCDAB
    CD
    \NPerl, PCRE (C, PHP, R…): one character that is not a line break\N+ABC
    \hPerl, PCRE (C, PHP, R…), Java: one horizontal whitespace character: tab or Unicode space separator
    \HOne character that is not a horizontal whitespace
    \v.NET, JavaScript, Python, Ruby: vertical tab
    \vPerl, PCRE (C, PHP, R…), Java: one vertical whitespace character: line feed, carriage return, vertical tab, form feed, paragraph or line separator
    \VPerl, PCRE (C, PHP, R…), Java: any character that is not a vertical whitespace
    \RPerl, PCRE (C, PHP, R…), Java: one line break (carriage return + line feed pair, and all the characters matched by \v)
    ### Logic
    LogicLegendExampleSample Match
    | Alternation / OR operand22|3333
    ( … )Capturing groupA(nt|pple)Apple (captures "pple")
    \1Contents of Group 1r(\w)g\1xregex
    \2Contents of Group 2(\d\d)+(\d\d)=\2+\112+65=65+12
    (?: … )Non-capturing groupA(?:nt|pple)Apple
    ### More Characters
    CharacterLegendExampleSample Match
    .Any character except line breaka.cabc
    .Any character except line break.whatever, man.
    \.A period (special character: needs to be escaped by a )a.ca.c
    \Escapes a special character.*+\?    \$\^\/\.+?    $^/\
    \Escapes a special character[{()}][{()}]
    ### Quantifiers
    QuantifierLegendExampleSample Match
    +One or moreVersion \w-\w+Version A-b1_1
    {3}Exactly three times\D{3}ABC
    {2,4}Two to four times\d{2,4}156
    {3,}Three or more times\w{3,}regex_tutorial
    Zero or more timesABCAAACC
    ?Once or noneplurals?plural
    ### Characters
    CharacterLegendExampleSample Match
    \dMost engines: one digit
    from 0 to 9
    file_\d\dfile25
    \d.NET, Python 3: one Unicode digit in any scriptfile\d\dfile_9੩
    \wMost engines: "word character": ASCII letter, digit or underscore\w-\w\w\wA-b1
    \w.Python 3: "word character": Unicode letter, ideogram, digit, or underscore\w-\w\w\w字-ま۳
    \w.NET: "word character": Unicode letter, ideogram, digit, or connector\w-\w\w\w字-ま‿۳
    \sMost engines: "whitespace character": space, tab, newline, carriage return, vertical taba\sb\sca b
    c
    \s.NET, Python 3, JavaScript: "whitespace character": any Unicode separatora\sb\sca b
    c
    \DOne character that is not a digit as defined by your engine's \d\D\D\DABC
    \WOne character that is not a word character as defined by your engine's \w\W\W\W\W\W-+=)
    \SOne character that is not a whitespace character as defined by your engine's \s\S\S\S\SYoyo