The original cheat sheet can be found here https://www.rexegg.com/regex-quickstart.html
| Character | Legend | Example | Sample Match |
|---|---|---|---|
| \d | Most engines: one digit from 0 to 9 | file_\d\d | file_25 |
| \w | Most engines: "word character": ASCII letter, digit or underscore | \w-\w\w\w | A-b_1 |
| \s | Most engines: "whitespace character": space, tab, newline, carriage return, vertical tab | a\sb\sc | a b c |
| \D | One character that is not a digit as defined by your engine's \d | \D\D\D | ABC |
| \W | One character that is not a word character as defined by your engine's \w | \W\W\W\W\W | *- =) |
| \S | One character that is not a whitespace character as defined by your engine's \s | \S\S\S\S | Yoyo |
| Character | Legend | Example | Sample Match |
|---|---|---|---|
| One or more | Version \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 times | ABC* | AAACC |
| ? | Once or none | plurals? | plural |
| Character | Legend | Example | Sample Match |
|---|---|---|---|
| . | Any character except line break | a.c | abc |
| . | Any character except line break | .* | whatever, man. |
| \. | A period (special character: needs to be escaped by a ) | a\.c | a.c |
| \ | Escapes a special character | \.\* ? $^/\\ | .* ? $^/\ |
| \ | Escapes a special character | \[\{(\)}\] | [{()}] |
| Character | Legend | Example | Sample Match |
|---|---|---|---|
| | | Alternation / OR operand | 22|33 | 33 |
| ( … ) | Capturing group | A(nt|pple) | Apple (captures "pple") |
| \. | A period (special character: needs to be escaped by a ) | a\.c | a.c |
| \ | Escapes a special character | \.\* ? $^/\\ | .* ? $^/\ |
| \ | Escapes a special character | \[\{(\)}\] | [{()}] |
| Character | Legend | Example | Sample Match |
|---|---|---|---|
| \t | Tab | T\t\w{2} | T ab |
| \r | Carriage return character | see below | |
| \n | Line feed character | see below | |
| \r\n | Line separator on Windows | AB\r\nCD | AB CD |
| Character | Legend | Example | Sample Match |
|---|---|---|---|
| The (one or more) is "greedy" | \d | 12345 | |
| ? | Makes quantifiers "lazy" | \d ? | 1 in 12345 |
| * | The * (zero or more) is "greedy" | A* | AAA |
| ? | 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 |
| Character | Legend | Example | Sample Match |
|---|---|---|---|
| [ … ] | One of the characters in the brackets | [AEIOU] | One uppercase vowel |
| [ … ] | One of the characters in the brackets | T[ao]p | Tap or Top |
| - | Range indicator | [a-z] | One lowercase letter |
| [ … ] | 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, including 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 |
| Character | Legend | Example | Sample Match |
|---|---|---|---|
| [ … ] | One of the characters in the brackets | [AEIOU] | One uppercase vowel |
| [ … ] | One of the characters in the brackets | T[ao]p | Tap or Top |
| - | Range indicator | [a-z] | One lowercase letter |
| [ … ] | 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, including 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 |
| Character | Legend | Example | Sample 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 |
| \A | Beginning of string (all major engines except JS) | \Aabc[\d\D]* | abc (string......start) |
| \z | Very end of the string Not available in Python and JS | the end\z | this is...\n...the end |
| \Z | End of string or (except Python) before final line break Not available in JS | the end\Z | this is...\n...the end |
| \G | Beginning of String or End of Previous Match .NET, Java, PCRE (C, PHP, R…), Perl, Ruby | ||
| \b | Word boundary Most engines: position where one side only is an ASCII letter, digit or underscore | Bob.*\bcat\b | Bob and the cat |
| \b | Word boundary .NET, Java, Python 3, Ruby: position where one side only is a Unicode letter, digit or underscore | Bob.*\b\кошка\b | Bob ate the кошка |
| \B | Not a word boundary | c.\Bcat\B. | copycats |
| Character | Legend | Example | Sample 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:]] | ‽,:〽⁆ |
| Character | Legend | Example | Sample Match |
|---|---|---|---|
| (?i) | Case-insensitive mode (except JavaScript) | (?i)Monday | monDAY |
| (?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 Z | From 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 Z | From A to Z |
| (?x) | Free-Spacing Mode mode (except JavaScript). Also known as comment mode or whitespace mode | ||
| (?n) | .NET, PCRE 10.30 : named capture only | Turns all (parentheses) into non-capture groups. To capture, use named groups. | |
| (?d) | Java: Unix linebreaks only | The dot and the ^ and $ anchors are only affected by \n | |
| (?^) | PCRE 10.32 : unset modifiers | Unsets ismnx modifiers |
| Character | Legend | Example | Sample Match |
|---|---|---|---|
| (?=…) | Positive lookahead | (?=\d{10})\d{5} | 01234 in 0123456789 |
| (?<=…) | Positive lookbehind | (?<=\d)cat | cat in 1cat |
| (?!…) | Negative lookahead | (?!theatre)the\w | theme |
| (?<!…) | Negative lookbehind | \w{3}(?<!mon)ster | Munster |