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Definition of Regular Expression

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Definition: A regular expression is a set of pattern matching rules encoded in a string according to certain syntax rules. Although the syntax is somewhat complex it is very powerful and allows much more useful pattern matching than say simple wildcards like ? and *.

Example of a Regular expression

 [-a-z0-9]+(\.[-a-z0-9]+)*
 

Regular expressions originated in the Unix world and are a part of the Perl language. If a regular expression language is similar to Perl's regular expressions, it is called Perl Compliant Regular expression (PCRE for short). This is pretty much a standard. The .NET framework includes pattern matching classes, as does Java.

Glossary:

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Also Known As: PCRE
Examples:
Regular Expressions can match complicated patterns.

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