The Need for This Book

I finished the first edition of this book in late 1996, and wrote it simply because there was a need. Good documentation on regular expressions just wasn't available, so most of their power went untapped. Regular-expression documentation was available, but it centered on the "low-level view." It seemed to me that they were analogous to showing someone the alphabet and expecting them to learn to speak.

Why I've Written the Second Edition

In the five and a half years since the first edition of this book was published, the world of regular expressions expanded considerably. The regular expressions of almost every tool and language became more powerful and expressive. Perl, Python, Tcl, Java, and Visual Basic all got new regular-expression backends. New languages with regular expression support, like Ruby, PHP, and C#, were developed and became popular. During all this time, the basic core of the book—how to truly understand regular expressions and how to get the most from them — maintained as important and relevant as ever.

Gradually, the first edition started to show its age. It needed updating to reflect the new languages and features, as well as the expanding role that regular expressions play in today's Internet world. When I decided to update the first edition, it was with a promise to my wife that it would take no more than three months. Two years later, luckily still married, almost the entire book has been rewritten from scratch. It's good, though, that it took so long, for it brought me into 2002, a particularly active year for regular expressions. In early 2002, both Java 1.4 (with java.util.regex) and Microsoft's .NET were released, and Perl 5.8 was released that summer. They are all covered fully in this book.