Pejman Moghadam / General

Regular Expressions

Public domain

Patterns of characters that are used in searching databases

MetacharacterMeaning ExampleExplanation
. Exactly one character, not null . One character, not null.
* zero or more times (like {0,}) ab*c ac, abc, abbc, abbbc, ...
+ once or more times (like {1,}) ab+c abc, abbc, abbbc, ...
? zero or once (like {0,1}) ab?c ac,abc.
^ Beginning of the line ^abc Lines witch begin with "abc".
$ End of the line abc$ Lines witch end with "abc".
\ Escape carahcter \. dot character.
[] One occurence of list [abc] matches a,b or c.
[-] Range of characters [a-d] matches a,b,c or d.
[^] Reverse range of characters [^a-d] matches not a,b,c or d.
(|) alternative text (abc|def) matches abc or def.
\d exactly one digit \d\d 00, 01, ..., 99.
\D everything except digit \D\D not 00,...,99.
\w exactly one letter,number or underscore (like [A-z0-9_]) \w a, 1, _, ....
\W everything except letter, number or underscore(like [^A-z0-9_]) \W @,#,...
\s exactly one whitespace (space,tab,newline) \s
\S everything except whitespace \S @
\b word boundary \bdef def (not abcdef)
\B non-word boundary \Bdef abcdef (not def)
\t tab character
\n carriage return
\nnn octal number \007 bell character
{m} character repetitions (m times) a{2} aa
{m,n} character repetitions (minimum m, maximum n) a{2,3} aa,aaa
{m,} character repetitions (minimum m) a{2,} aa,aaa,aaaa,aaaaa,...

BY: Pejman Moghadam
TAG: regex
DATE: 2009-04-25 00:16:37

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