54 lines
4.8 KiB
Markdown
54 lines
4.8 KiB
Markdown
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[https://cheatography.com/davechild/cheat-sheets/regular-expressions/](https://cheatography.com/davechild/cheat-sheets/regular-expressions/)
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```
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Anchors Quantifiers Groups and Ranges
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^ Start of string, or start of line in multi-line pattern * 0 or more {3} Exactly 3 . Any character except new line (\n)
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\A Start of string + 1 or more {3,} 3 or more (a|b) a or b
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$ End of string, or end of line in multi-line pattern ? 0 or 1 {3,5} 3, 4 or 5 (...) Group
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\Z End of string Add a ? to a quantifier to make it ungreedy. (?:...) Passive (non-capturing) group
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\b Word boundary [abc] Range (a or b or c)
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\B Not word boundary Escape Sequences [^abc] Not (a or b or c)
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\< Start of word [a-q] Lower case letter from a to q
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\> End of word \ Escape following character [A-Q] Upper case letter from A to Q
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\Q Begin literal sequence [0-7] Digit from 0 to 7
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Character Classes \E End literal sequence \x Group/subpattern number "x"
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Ranges are inclusive.
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\c Control character
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\s White space Pattern Modifiers
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\S Not white space Common Metacharacters
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\d Digit g Global match
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\D Not digit ^ [ . $ i * Case-insensitive
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\w Word { * ( \ m * Multiple lines
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\W Not word + ) | ? s * Treat string as single line
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\x Hexadecimal digit < > x * Allow comments and whitespace in pattern
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\O Octal digit The escape character is usually \ e * Evaluate replacement
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U * Ungreedy pattern
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POSIX Special Characters * PCRE modifier
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[:upper:] Upper case letters \n New line String Replacement
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[:lower:] Lower case letters \r Carriage return
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[:alpha:] All letters \t Tab $n nth non-passive group
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[:alnum:] Digits and letters \v Vertical tab $2 "xyz" in /^(abc(xyz))$/
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[:digit:] Digits \f Form feed $1 "xyz" in /^(?:abc)(xyz)$/
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[:xdigit:] Hexadecimal digits \xxx Octal character xxx $` Before matched string
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[:punct:] Punctuation \xhh Hex character hh $' After matched string
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[:blank:] Space and tab $+ Last matched string
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[:space:] Blank characters $& Entire matched string
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[:cntrl:] Control characters Some regex implementations use \ instead of $.
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[:graph:] Printed characters
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[:print:] Printed characters and spaces
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[:word:] Digits, letters and underscore
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Assertions
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?= Lookahead assertion
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?! Negative lookahead
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?<= Lookbehind assertion
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?!= or ?<! Negative lookbehind
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?> Once-only Subexpression
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?() Condition [if then]
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?()| Condition [if then else]
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?# Comment
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```
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