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  • 1. Regular Expressions Cheat Sheet by Dave Child (DaveChild) via Regular Expressions Anchors Regular Expressions Quantifiers Regular Expressions Groups and Ranges ^ Start of string, or start of line in multi-line pattern * 0 or more . Any character except new line (n) A Start of string + 1 or more (a|b) a or b $ End of string, or end of line in multi-line pattern ? 0 or 1 (...) Group Z End of string {3} Exactly 3 (?:...) Passive (non-capturing) group b Word boundary {3,} 3 or more [abc] Range (a or b or c) B Not word boundary {3,5} 3, 4 or 5 [^abc] Not a or b or c < Start of word Add a ? to a quantifier to make it ungreedy. [a-q] Letter from a to q > End of word [A-Q] Upper case letter from A to Q Regular Expressions Escape Sequences [0-7] Digit from 0 to 7 Regular Expressions Character Classes Escape following character n nth group/subpattern c Control character Q Begin literal sequence Ranges are inclusive. s White space E End literal sequence S Not white space "Escaping" is a way of treating characters which have Regular Expressions Pattern Modifiers d Digit a special meaning in regular expressions literally, g Global match D Not digit rather than as special characters. i Case-insensitive w Word m Multiple lines W Not word s Treat string as single line x Hexadecimal digit x Allow comments and white space in pattern O Octal digit e Evaluate replacement U Ungreedy pattern Regular Expression Common Metacharacters ^ [ . $ { * ( + Regular Expressions POSIX ) | ? [:upper:] Upper case letters < > [:lower:] Lower case letters The escape character is usually the backslash - . [:alpha:] All letters [:alnum:] Digits and letters [:digit:] Digits [:xdigit:] Hexadecimal digits [:punct:] Punctuation [:blank:] Space and tab [:space:] Blank characters [:cntrl:] Control characters [:graph:] Printed characters [:print:] Printed characters and spaces [:word:] Digits, letters and underscore Regular Expressions Special Characters n New line r Carriage return t Tab v Vertical tab f Form feed xxx Octal character xxx xhh Regular Expressions String Replacement $n nth non-passive group $2 "xyz" in /^(abc(xyz))$/ $1 "xyz" in /^(?:abc)(xyz)$/ $` Before matched string $' After matched string $+ Last matched string $& Entire matched string Hex character hh Some regex implementations use instead of $. Regular Expressions Assertions ?= Lookahead assertion ?! Negative lookahead ?<= Lookbehind assertion ?!= or ?<! Negative lookbehind ?> Once-only Subexpression ?() Condition [if then] ?()| Condition [if then else] ?# Comment Cheatographer Cheat Sheet Sponsor Dave Child (DaveChild) This cheat sheet was published on 19th October, 2011 FeedbackFair, increase your conversion rate today! and was last updated on 14th November, 2012. Try it free!