Learning Regular Expressions
Learning Series

Learn to use one of the most powerful text processing and manipulation tools available

Regular expression experts have long been armed with an incredibly powerful tool, one that can be used to perform all sorts of sophisticated text processing and manipulation in just about every language and on every platform. That?s the good news. The bad news is that for too long, regular expressions have been the exclusive property of only the most tech savvy. Until now.

Ben Forta's Learning Regular Expressions teaches you the regular expressions that you really need to know, starting with simple text matches and working up to more complex topics, including the use of backreferences, conditional evaluation, and look-ahead processing. You?ll learn what you can use, and you?ll learn it methodically, systematically, and simply.

Regular expressions are nowhere near as complex as they appear to be at first glance. All it takes is a clear understanding of the problem being solved and how to leverage regular expressions to solve them.

• Read and understand regular expressions
• Use literal text and metacharacters to build powerful search patterns
• Take advantage of advanced regular expression features, including lookahead and backreferences
• Perform powerful search-and-replace operations in all major professional editing tools
• Add sophisticated form and text processing to web applications
• Search for files using command-line tools like grep and egrep
• Use regular expressions in programming languages like JavaScript, Java, PHP, Python, Microsoft .NET, and C#, as well as in DBMSs including MySQL and Oracle
• Work with phone numbers, postal codes, social security numbers, IP addresses, URLs, email addresses, and credit card numbers

Introduction 1

Chapter 1 Introducing Regular Expressions 3

Understanding the Need 3

How Regular Expressions Are Used 4

RegEx Searches 4

RegEx Replaces 5

So What Exactly Is a Regular Expression? 5

Using Regular Expressions 6

Before You Get Started 7

Summary 7

Chapter 2 Matching Single Characters 9

Matching Literal Text 9

How Many Matches? 10

Handling Case Sensitivity 10

Matching Any Characters 11

Matching Special Characters 14

Summary 16

Chapter 3 Matching Sets of Characters 17

Matching One of Several Characters 17

Using Character Set Ranges 20

“Anything But” Matching 23

Summary 24

Chapter 4 Using Metacharacters 25

Escaping Revisited 25

Matching Whitespace Characters 28

Matching Specific Character Types 29

Matching Digits (and Nondigits) 29

Matching Alphanumeric Characters (and Nonalphanumeric Characters) 31

Matching Whitespace (and Nonwhitespace) 32

Specifying Hexadecimal or Octal Values 32

Using POSIX Character Classes 33

Summary 35

Chapter 5 Repeating Matches 37

How Many Matches? 37

Matching One or More Characters 38

Matching Zero or More Characters 40

Matching Zero or One Characters 42

Using Intervals 44

Exact Interval Matching 44

Range Interval Matching 45

“At Least” Interval Matching 46

Preventing Over Matching 48

Summary 49

Chapter 6 Position Matching 51

Using Boundaries 51

Using Word Boundaries 52

Defining String Boundaries 54

Using Multiline Mode 57

Summary 58

Chapter 7 Using Subexpressions 59

Understanding Subexpressions 59

Grouping with Subexpressions 60

Nesting Subexpressions 63

Summary 66

Chapter 8 Using Backreferences 67

Understanding Backreferences 67

Matching with Backreferences 70

Performing Replace Operations 73

Converting Case 75

Summary 76

Chapter 9 Looking Ahead and Behind 77

Introducing Lookaround 77

Looking Ahead 78

Looking Behind 80

Combining Lookahead and Lookbehind 82

Negating Lookaround 83

Summary 85

Chapter 10 Embedding Conditions 87

Why Embed Conditions? 87

Using Conditions 88

Backreference Conditions 88

Lookaround Conditions 90

Summary 92

Chapter 11 Regular Expression Solutions to Common Problems 93

North American Phone Numbers 93

U.S. ZIP Codes 95

Canadian Postal Codes 95

United Kingdom Postcodes 96

U.S. Social Security Numbers 97

IP Addresses 98

URLs 98

Complete URLs 99

Email Addresses 100

HTML Comments 101

JavaScript Comments 102

Credit Card Numbers 103

Summary 107

Appendix A Regular Expressions in Popular Applications and Languages 109

grep 109

Java 110

JavaScript 111

Microsoft .NET 111

Microsoft SQL Server T-SQL 112

Microsoft Visual Studio .NET 112

MySQL 113

Oracle PL/SQL 114

Perl 114

PHP 115

Python 116

9780134757063 TOC 4/5/2018

Ben Forta is Adobe Systems’ Senior Director of Education Initiatives. He is also the author of numerous books on SQL, regular expressions, ColdFusion, Windows development, JSP, and more. His book Teach Yourself SQL in 10 Minutes is the best-selling book on SQL of all time.

• Packed with complete examples and detailed usage notes
• Includes test code in multiple languages so readers can use the examples immediately
• Covers regex with grep, JavaScript, C#, .NET, Visual Studio, MySQL, Perl, PHP, and Java