Regular Expressions Cheat Sheet

Regular Expressions Cheat Sheet by DaveChild

Source: 
cheatography.com

Regular Expressions Anchors ^ Start of string, or start of line in multi-line pattern \A Start of string $ End of string, or end of line in multi-line pattern \Z End of string \b Word boundary \B Not word boundary \< Start of word \> End of word Regular Expressions Character Classes \c Control character \s White space \S Not white space \d Digit \D Not digit \w Word \W Not word \x Hexadecimal digit \O Octal digit Regular Expressions POSIX [:upper:] Upper case letters [:lower:] Lower case letters [: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 Assertions ?= Lookahead assertion ?! Negative lookahead ?<= Lookbehind assertion ?!= or ?<! Negative lookbehind ?> Once-only Subexpression ?() Condition [if then] ?()| Condition [if then else] ?# Comment

Regular Expressions Quantifiers * 0 or more + 1 or more ? 0 or 1 {3} Exactly 3 {3,} 3 or more {3,5} 3, 4 or 5 Add a ? to a quantifier to make it ungreedy. Regular Expression Common Metacharacters ^ [ . $ { * ( \ + ) | ? < > The escape character is usually the backslash - \. Regular Expressions Special Characters \n New line \r Carriage return \t Tab \v Vertical tab \f Form feed \xxx Octal character xxx \xhh Hex character hh

Download a PDF of the Regular Expressions cheat sheet! Regular Expressions Groups and Ranges . Any character except new line (\n) (a|b) a or b (...) Group (?:...) Passive (non-capturing) group [abc] Range (a or b or c) [^abc] Not a or b or c [a-q] Letter from a to q [A-Q] Upper case letter from A to Q [0-7] Digit from 0 to 7 \n nth group/subpattern Ranges are inclusive. Regular Expressions Pattern Modifiers g Global match i Case-insensitive m Multiple lines s Treat string as single line x Allow comments and white space in pattern e Evaluate replacement U Ungreedy pattern 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 Some regex implementations use \ instead of $.