Beginning Regular Expressions

771 Pages·2005·24.355 MB·English

by  Andrew Watt

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Beginning Regular Expressions
Andrew Watt
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Beginning Regular Expressions
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Beginning Regular Expressions
Andrew Watt
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Beginning Regular Expressions
Published by
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Copyright © 2005 by Wiley Publishing, Inc., Indianapolis, Indiana
Published simultaneously in Canada
ISBN: 0-7645-7489-2
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Library of Congress Cataloging-in-Publication Data:
Watt, Andrew, 1953-
Beginning regular expressions / Andrew Watt.
p. cm.
ISBN 0-7645-7489-2 (paper/website)
1. Text processing (Computer science) I. Title.
QA76.9.T48W37 2005
005.52—dc22
2004028308
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About the Author
Andrew Watt is an independent consultant and experienced author with an interest and expertise in
XMLand Web technologies. He has written and coauthored more than 10 books on Web development
and XML, including XPath Essentials and XMLSchema Essentials. He has been programming since 1984,
moving to Web development technologies in 1994. He’s a well-known voice in several influential online
technical communities and is a frequent contributor to many Web development specifications.
Dedication
I would like to dedicate this book to the memory of my late father, George Alec Watt, a very special
human being.
Acknowledgments
Authors often state that a book is the work of a team rather than a single person. There is a good reason
for that assertion. It’s true.
First, I would like to thank Jim Minatel, the acquisitions editor who put the platform in place to get
Beginning Regular Expressionsoff the ground at Wrox/Wiley. His patience, under significant provocation
relating to timetable, and his tact, efficiency, and general good nature made those organizational aspects
of the book an enjoyable experience to repeat at a future date.
The development editor, Marcia Ellett, was great to work with and did a lot to tidy up my prose to make
a better read for all readers of this book. In addition, her eagle eyes spotted some minor slips that had
slipped through the authorial net. Thanks, Marcia.
Doug Steele, a fellow Microsoft MVP, was technical editor and carried out a tactful and painstaking job
and picked up many little things that the smoke from the author’s midnight oil seemed somehow to
obscure. Thanks, Doug.
Darren Niemke, another MVP, helped with technical editing of a number of chapters. Thanks, Darren.
My thanks go, too, to the production staff at Wiley who, as is typically the case, the author never meets.
Without their efforts in translating a manuscript into a finished product this book would not exist in its
current form.
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Credits
Acquisitions Editor Editorial Manager
Jim Minatel Mary Beth Wakefield
Development Editor Vice President & Executive Group Publisher
Marcia Ellett Richard Swadley
Technical Editors Vice President and Publisher
Douglas J. Steele Joseph B. Wikert
Darren Neimke
Project Coordinator
Production Editor April Farling
Felicia Robinson
Media Development Specialist
Copy Editor Angie Denny
Jeri Freedman/Foxxe Editorial Services
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Contents
Introduction xxi
Who This Book Is For xxi
What This Book Covers xxii
How This Book Is Structured xxii
What You Need to Use This Book xxiii
Conventions xxiii
Source Code xxiv
Errata xxiv
p2p.wrox.com xxv
Chapter 1: Introduction to Regular Expressions 1
What Are Regular Expressions? 2
What Can Regular Expressions Be Used For? 5
Finding Doubled Words 5
Checking Input from Web Forms 5
Changing Date Formats 6
Finding Incorrect Case 6
Adding Links to URLs 6
Regular Expressions You Already Use 7
Search and Replace in Word Processors 7
Directory Listings 7
Online Searching 8
Why Regular Expressions Seem Intimidating 8
Compact,Cryptic Syntax 8
Whitespace Can Significantly Alter the Meaning 9
No Standards Body 12
Differences between Implementations 12
Characters Change Meaning in Different Contexts 13
Regular Expressions Can Be Case Sensitive 15
Case-Sensitive and Case-Insensitive Matching 15
Case and Metacharacters 16