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A regex search scans the text of each page on Wikipedia in real time, character by character, to find pages that match a specific sequence or pattern of characters. Unlike keyword searching, regex searching is by default case-sensitive, does not ignore punctuation, and operates directly on the page source (MediaWiki markup) rather than on the ...
Normally searches ignore non-alphanumeric characters, but regular expressions (regex) accept all characters, plus metacharacters. This template acts as a doorway by helping to develop a database query before running it on the wiki, and it does this by way of a search link that can also be used to share such discoveries.
Algebraic laws for regular expressions can be obtained using a method by Gischer which is best explained along an example: In order to check whether (X+Y) ∗ and (X ∗ Y ∗) ∗ denote the same regular language, for all regular expressions X, Y, it is necessary and sufficient to check whether the particular regular expressions (a+b) ∗ and ...
Like word searches and exact-phrase searches, non-alphanumeric characters are ignored, and proximity and fuzziness are options. insource:/regexp/ insource:/regexp/i: These are regular expressions. They use a lot of processing power, so we can only allow a few at a time on the search cluster, but they are very powerful.
A change from a numeric to an alphanumeric character is an additional word boundary in an alphanumeric word. A change from an alphanumeric to a numeric character is a word boundary in an alphanumeric word. A change in case from lowercase to uppercase is a word boundary in an alphabetic word.
Regular expressions compactly represent patterns that the characters in lexemes might follow. For example, for an English -based language, an IDENTIFIER token might be any English alphabetic character or an underscore, followed by any number of instances of ASCII alphanumeric characters and/or underscores.
Perl Compatible Regular Expressions (PCRE) is a library written in C, which implements a regular expression engine, inspired by the capabilities of the Perl programming language. Philip Hazel started writing PCRE in summer 1997. [ 3 ]
Regular Expression Flavor Comparison – Detailed comparison of the most popular regular expression flavors; Regexp Syntax Summary; Online Regular Expression Testing – with support for Java, JavaScript, .Net, PHP, Python and Ruby; Implementing Regular Expressions – series of articles by Russ Cox, author of RE2; Regular Expression Engines