PARSING
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This is an introduction to regular expressions for those of you that have heard the phrase “just use a regular expression on that string to extract the data…” but doesn’t understand the thing about a “regular expression”. I’ll write RE instead of “regular expression” from now on to save me some typing. The phrase given above hints that one should use a RE on a text string and that it can be used to extract data from such a string. This is what a RE does: it matches something. A RE is a short way of representing a potentially very complex pattern that is to be matched against a string of characters.
Martin Geisler Online » Regular Expressions
A Regular Expression is the term used to describe a codified method of searching invented , or defined , by the American mathematician Stephen Kleene. The syntax (language format) described on this page is compliant with extended regular expressions (EREs) defined in IEEE POSIX 1003.2 (Section 2.8). EREs are now commonly supported by Apache, PERL, PHP4, Javascript 1.3+, MS Visual Studio, most visual editors, vi, emac, the GNU family of tools (including grep, awk and sed) as well as many others. Extended Regular Expressions (EREs) will support Basic Regular Expressions (BREs are essentially a subset of EREs). Most applications, utilities and laguages that implement RE's, especially PERL, extend the capabilities defined and this has become, mostly, the de facto standard.
Regular Expressions - a Simple User Guide
<p class="center">Please enable javascript to best experience this site.</p> This document explains how to construct a compiler using lex and yacc.
Lex & Yacc
BNF and EBNF: What are they and how do they work?
By: Lars Marius Garshol Contents Introduction What is this?