Chapter 1. Regular Expression Pocket Reference

Regular expressions (known as regexps or regexes) are a way to describe text through pattern matching. You might want to use regular expressions to validate data, to pull pieces of text out of larger blocks, or to substitute new text for old text.

Regular expression syntax defines a language you use to describe text. Today, regular expressions are included in most programming languages as well as many scripting languages, editors, applications, databases, and command-line tools. This book aims to give quick access to the syntax and pattern-matching operations of the most popular of these languages.