Regular expression examples: Difference between revisions

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{{examplefarm}}

A [[regular expression]] ( also "RegEx" or "regex" ) is a string that is used to describe or match a set of strings according to certain [[syntax]] rules. The specific syntax rules vary depending on the specific [[implementation]], [[programming language]], or [[Library (computing)|library]] in use. Additionally, the functionality of regex implementations can vary between [[Software versioning|version]]s.

Despite this variability, and because regular expressions can be difficult to both explain and understand without examples, this article provides a basic description of some of the properties of regular expressions by way of illustration.

== Conventions ==

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metacharacter(s) ;; the metacharacters column specifies the regex syntax being demonstrated

=~ m// ;; indicates a regex '''match''' operation in perl

=~ s/// ;; indicates a regex '''substitution''' operation in perl

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== Examples ==

Unless otherwise indicated, the following examples conform to the [[Perl]] programming language, release 5.8.8, January 31, 2006. The syntax and conventions used in these examples coincide with that of other programming environments as well (e.g., see Java in a Nutshell - — Page 213, Python Scripting for Computational Science - — Page 320, Programming PHP - — Page 106 ).

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<td>( )</td>

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<td>?</td>

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<td>*</td>

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<td>{M,N}</td>

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<td>[...]</td>

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<td>|</td>

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<td>\b</td>

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<td>\w</td>

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<td>\W</td>

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<td>\S</td>

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<td>\d</td>

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<td>\D</td>

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<td>^</td>

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<td>$</td>

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[[Category:Articles with example code]]

[[Category:Programming language topics]]

==External links==

* [http://regex.powertoy.org/ simple and straitforward RegEx online trainer/demo]