I am using them since my Perl-days … so I found this a great introduction with hidden gems1! Also check out the online-tool from Lea Verou for playing around with regular expressions online: http://leaverou.github.io/regexplained/.
A regular expression (shortened as regex or regexp; also referred to as rational expression) is a sequence of characters that specifies a search pattern. Usually such patterns are used by string-searching algorithms for "find" or "find and replace" operations on strings, or for input validation. It is a technique developed in theoretical computer science and formal language theory.
The concept of regular expressions began in the 1950s, when the American mathematician Stephen Cole Kleene formalized the description of a regular language. They came into common use with Unix text-processing utilities. Different syntaxes for writing regular expressions have existed since the 1980s, one being the POSIX standard and another, widely used, being the Perl syntax.
Regular expressions are used in search engines, search and replace dialogs of word processors and text editors, in text processing utilities such as sed and AWK and in lexical analysis. Many programming languages provide regex capabilities either built-in or via libraries, as it has uses in many situations.
Definition from Wikipedia – Regular expression
Lea Verou (Greek: Λία Βέρου; born June 13, 1986) is a front end web developer, speaker and author, originally from Lesbos, Greece. Verou is currently a Research Assistant at MIT CSAIL, in David Karger’s Haystack group and an Invited Expert in the W3C CSS Working Group.Verou has written a book on advanced CSS for O’Reilly, worked for W3C/MIT, given over 60 invited talks around the world, released several open source projects, and co-founded a Greek startup called Fresset Ltd (which she left in 2011), among other projects. She has written articles for several magazines in the Web design industry, including A List Apart and Smashing Magazine.
Definition from Wikipedia – Lea Verou
- recommendation via Andre Michelle ↩