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Examples
Examples
| Submit | Regular Expression | Input String |
|---|---|---|
| foo | foo the foo when you foo | |
| [bcr]at | cats chase rats, bats fly | |
| [^bcr]at | cats chase rats, bats fly and wear hats | |
| [a-f]at | cats chase rats, bats fly and wear hats | |
| [0-4[6-8]] | 2 7 9 5 3 0 | |
| [0-9&&[345]] | 2 7 9 5 3 0 | |
| [0-9&&[^345]] | 2 7 9 5 3 0 | |
| a? | ababaaaab | |
| a* | ababaaaab | |
| a+ | ababaaaab | |
| a{3} | ababaaaab | |
| a{3,} | ababaaaaaa | |
| a{3,5} | ababaaaaaa | |
| (dog){3} | dogdogdogdogdogdog | |
| .*foo | xfooxxxxxxfoo | |
| .*?foo | xfooxxxxxxfoo | |
| .*+foo | xfooxxxxxxfoo | |
| (..)\1 | abab ccc cdcd | |
| ^piggy$ | piggy | |
| \bpig\b | piggy eat pig |
Meta Characters
| ( ) |
Define Capturing Groups
Allows a group of characters to be treated as a single unit Capturing Groups are numbered according to the number of opening parentheses left to right. |
| [ ] | Defines character class |
| \n |
Back reference captured group n
Escape Character when used by itself \ |
| | | OR |
| && | Intersection Operator |
| . | Any single character May or may not match line terminators |
| , | Bound number of matches |
| Quantifiers | |
|---|---|
| ? |
Match once or not at all
Also append to quantifier to create Reluctant Quantifier |
| * | Match zero or more times |
| + |
Match one or more times
Also append to quantifier to create Possessive Quantifier |
| {n} | Match pattern n times |
| Boundary Matchers | |
| ^ |
Match beginning of a line
Negation when used in character class |
| $ | Match end of a line |
| \b | Word boundary |
| \B | Non-word boundary |
| \A | Beginning of input |
| \G | End of previous match |
| \Z | End of input but before final terminator, if any |
| \z | End of input |
| Predefined Character Ranges | |
| \d | A single digit [0-9] |
| \D | A single non-digit [^0-9] |
| \s | A single whitespace character [ \t\n\x0B\f\r] |
| \S | A single non-whitespace character [^\s] |
| \w | A single word character [a-zA-Z_0-9] |
| \W | A single non-word character [^\w] |
| Embedded Flag Expressions | |
| (?i) | Case Insensitive |
| (?x) | Comments - whitespace and # until end of line ignored |
| (?m) | Multi line |
| (?s) | Dot "." matches line terminators too |
| (?u) | Unicode |
| (?d) | Unix lines |
|
Precede meta character with backslash to have it be treated like
an ordinary character
Or enclose it within \Q and \E (start quote, end quote) |
|
Notes
- Index ranges are inclusive of the beginning index and exclusive of the end index.
by: Keith A. Pray
Last Modified: April 15, 2009 11:27 PM
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© 2009 - 1975 Keith A. Pray.
All rights reserved. |