This book is great if you want to learn about what you can do with regex, how they work, how you can improve them (efficiency & accuracy) and what kind of pitfalls there are.

My only gripe is about the Ruby reference on the cover. In the top right corner it says: "For Perl, PHP, Java, .NET, Ruby and more!" Perl, Java, .NET and PHP each get their own chapters (together 200 pages). Ruby, however, only participates in feature comparisons and benchmarks. If I had checked the ToC I would've known this, so I won't hold it against the book that much.

The Ruby thing is a bummer, but since the book is great, it will get all five stars.

The book is robust and goes into alot detail. I liked the comparing and contrasting between the various RegEx implementations. I had a difficult time digesting some of the detail. In particular, the analogies confused me and I felt the author went overboard with them. Many times, I had to backtrack to understand what was being discussed. However, regular expressions is a complex topic and the author did a good job easing into the concepts. An additional plus was with inline page citation - this helped to find the page corresponding to the topic being discussed.
I would have liked shorter chapters with chapter summaries and more diagrams in place of analogies. Ultimately, Mastering Regular Expressions is a good book referencing a complex topic.

I went through several books and online tutorials and never found anything that did a good comprehensive job of explaining regular expressions. This book does. If you are having trouble "getting it", I highly encourage reading this book. You will be extremely enlightened even after the first few chapters.

Quite a comprehensive guide to regular expressions. Gets very detailed in the areas that it covers. However, definitely not a 'beginner's guide'. I highly recommend that you are already comfortable with the basis of regular expressions before picking up this book. You will get way more out of it if this is not your first introduction to it. Comfort and proficiency with Perl would also be a big help. Title is correct though, this is a guide to 'mastering' regular expressions, not learning them from the beginning.

How deep down the rabbit hole do you really NEED to go? I had a serious need to get on top of regular expressions to solve one particular problem. I looked at several online tutorials which didn't take me where I needed to go, so I ordered Mastering Regular Expressions after reading the Amazon reviews. I always look at the negative reviews first. In spite of the negative reviews I ordered the book with an open mind.
When the book arrived I began reading it with enthusiasm. In the preface there is a small section on "How to Read This Book". I bought into the author's suggestion to read the book's first six chapters first. I was captivated through the first three chapters, and then somewhere in chapter 4 I began to get very weary with information overload. After putting the book down for a couple of days I decided to skip the rest and use what I needed to write the one regular expression I had need of. The book did successfully help me accomplish this, so I gave it 3 stars. Not only did it give me the information I needed that the online tutorials didn't, it also gave me the confidence I needed. For that, which I am grateful, I would have liked to have given it more stars. I think many of those in need of learning about regular expression could be well served by a "lite-edition" of this book. Perhaps someday when I have the time and the need I may try to wade through the rest of the book, but as it is now Mastering Regular Expressions took me far farther down the rabbit hole than I really needed or wanted to go.
If you need to get on top of Regular Expressions, I would recommend this book, however just be ready to be taken far deeper than the average coder probably needs to go.

An incredible book. Absolutely incredible. It will take 200 lines of your code and reduce it to 1 or 2 lines. It will open your mind to search and replace possibilities. Your life will change (just kidding). It's a great deep book.

However, I agree with the comment that one should not begin learning regex with this book. it's a little too advanced. Go on the internet, get an introduction. Or else, buy one of the introductory books on the subject first. But definitely get around to buying this book!

This book is seriously worth the money. I knew just enough regular expressions to get by, then I started reading this book and it has paid off already; saving me time on several long, arduous tasks.

The book is really well written, very interactive w/ quick, quizzing questions mixed throughout the chapters. The authors writing style is very effective and surprisingly entertaining.

If you don't know much about regular expressions or even if you think you do, purchase this book. It will be well worth it.

I have been in computer software developer over 7 years now and never really used regular expression until a year ago. True, you can live without it. But, with regular expression at hand, you climb up another level of programming. Code will be much concise and code research will be like a breeze.

Anyway, I didn't read this book entirely since later chapters explain intricacies and subtle differences of each specific language, e.g., java, perl, php, etc. It didn't take long to apply the knowledge I gained to real work and benefit. By the time I completed the first chapter, I already started to get rewards. My life is a lot easier now.

Even with only the first 3 chapters, this book is well worth its price. The author did superb job explaining what's going on behind the scene and guide you through the right way of constructing regular expressions for various situations. Of course, he will show you common pitfalls to avoid, too. Very detailed and comprehensive.

Highly recommended.

Before reading this book, I would have considered myself an intermediate regexer. After the first 2 chapters, I realized how novice I really was. Having only made it through 5 chapters of this book, I can't say enough about it. The detail and step-by-step analysis that Mr. Friedl takes to describe the regex matching process is the best I've ever seen. It's little things that make the analysis easy to follow -- like the brackets he uses to mark the regex, and the small triangle cursor to show where the engine is in the matching process. I continue to look forward to each new chapter. Thank you for a wonderful work of art.

Are you a programmer working on text-related tasks? If you are, then this book is for you. Author Jeffrey Friedl, has done an outstanding job of writing a cool book that will interest anyone who has an opportunity to use regular expressions.

Friedl, begin with an introduction to the concept of regular expressions. Then, the author takes a look at text processing with regular expressions. Next, the author provides an overview of features and utilities, plus a bit of history. He also explains the details of how regular expressions work. The author continues by working through regular expressions examples. Then, he discusses efficiency in detail. Next, the author covers Perl regular expressions in detail. He then looks at Sun's java.util.regex package. The author continues by looking at .NET's language-neutral regular-expression package. Finally, the author looks at PHP's preg suite of regex functions.

This most excellent book should expand your understanding, even if you consider yourself an accomplished regular-expression expert. Perhaps more importantly, the book concentrates on mastering a particular implementation!

Many people only barely utilize regular experssions, having been unable to get more than basic expressions to work. There are a lot of reasons for this - shell escapes, man pages that are terse to the point of being cryptic, etc. This book is a clear and very readable trip through practical regular expression creation and application that will enable the reader to get the most out of grep, awk, perl and other programs that use regular expressions.

Jeffrey Friedl describes regular expressions at an amazing depth and precision. Regular expressions are not easy and the quirks of the different tools (including their exact version and for what operating system) make writing them to an irritating black art. A black art to almost anybody. MRE sorts everything out in a comprehensible fashion. The price the reader has to pay: a very dense book, a need to follow the details until your head starts swimming and a lot of strain on the memory about what works, how and where.


MRE is somewhat easier to comprehend for a reader with a strong Pearl background. Also a good prior understanding to regular expressions is a true asset here. If you have neither, you do not need to despair. Jeffrey Friedl explains everything thoroughly from the ground up.


The writing style is very pedagogical. Important things get repeated quite often. Still this book is very dense. The flow is dry: no rhythm, special sense of humor or wit sweetens your wading through the material. Nevertheless Jeffrey Friedl kept my interest through the pages though the reading felt like hard work.

I do recommend this book to the truly dedicated reader.

This is must-have if you are trying to learn regexps or improve your knowledge of them. It carefully walks you through how to construct expressions, covering everything from the most basic tasks to complicated scenarios. It explains how matching works, so you can really understand what is going on behind the scenes.

What more can I say besides what everyone else has said.
This is a WONDERFUL and POWERFUL book on Regular Expressions.

From just-beyond-beginner to advanced, this book provides a fantastic view into the world of Regular Expressions and the practical thinking involved with them. However, without at least a semi-understanding of the concepts you will not be able to get through the book very quickly.

I walked away with MUCH more knowledge than I had expected to. This applies to not only regular expressions, but also to rational thinking/planning when it comes to data and programmatic analysis.

This is a great book for learning about regular expressions. It goes into much detail, yet still remains an easy read for a novice who has not had much experience to RegEx. Recommended.

This is a great book for learning about regular expressions. It goes into much detail, yet still remains an easy read for a novice who has not had much experience to RegEx. Recommended.

Regular Expressions need to be fully mastered in order to truly gain access to the power of many languages and programs. Whether you are working with Perl, PHP, Java, .NET, Ruby, C, Python or any of a variety of other languages the use of regular expressions allows you to work with your data in powerful ways. As a general rule most books that even mention regular expressions just mention a very few of the common ways to build an expression. This book takes the reader well beyond that level and explores the many more unusual ways regular expressions can be used. If you don't know what a regular expression is then you have no need for this book, but if you have ever worked with regular expressions then you are in for a treat with this book. I have used them for years and built a whole spam filter system around regular expressions but there is so much more they can do and this book can make you an expert.

After a basic introduction covering the most common tasks regular expressions are used for (substitution, selection, wild cards, etc.) the author delves into examples of regular expressions in Perl, and follows that with a section discussing some of the variations in regular expressions as implemented in different languages and common programs. One of the most important features of the book is the plethora of real world programming examples. Mastering Regular Expressions is highly recommended to anyone who wants to completely master the full art of regular expressions.

Regular expressions are not really for the person playing at would-be programmer. It is to the text processing person what a top-of-the-line drill is to a carpenter. It requires a dedication to detail, an ability to write out exactly what needs to be done and why it works. Regexs are used in a context. Perl for example, helps the process along by supplying a well-packaged and documented environment for regex. But this means you have to learn Perl, or Java, or PHP, Python, Ruby, whatever. This book is for the kind of person that fits somewhere in the above described mix. It is however, THE book to have when you do care enough. It is not an easy book for a beginner or those in a hurry. Whatever it is that is covered here is done well and authoritatively (spelling ?). The author knows his stuff and the pains-taking effort he talks about in his Preface is obvious to the student of the book.
I believe this topic lends itself to being best taught by looking hard at a big bunch of non-trivial examples, with a lot of surrounding comments. They are in the book, I wish there were more. Perhaps the buyers of this book, along with the regex gurus out there could start posting well-crafted regexs to some well-known spot. I believe that O'Reiily, the publisher of this boo already might have such a posting site.
Kudos to O'Reilly and to the author for a wonderful contribution to the computer programmer/science community

Regular Expressions can be confusing unless you use them everyday. This book is a great quick reference and will provide the deeper level information you need for those harder solution.

For many savvy computer users, regular expressions embody the perfect utility: a well defined, documented, and designed tool that makes complicated and arduous jobs short and easy. That being said, the craft of regular expressions (hereafter, `regex') makes about as much sense as a foreign language to the uninitiated or novice. Regex have no immediately apparent meaning to those unfamiliar with them, and are so enigmatic in appearance that many users do not even attempt to understand them - writing them off as a tool only for experts. "Mastering Regular Expressions" sets out to not only make regex understandable, but easy to apply to a wide range of situations.

Stylistically and structurally, this is one of the most unique O'Reilly publications I have read. The author even says in the early chapters to think of the book as a novel, and not as a reference (the book's structure doesn't really lend itself to being a reference book anyways). The mindset that the author applies to his writing makes a discernable difference in how the book reads, and it feels more like a chronological story and less like a textbook as a result. Even the quizzes that the author scatters throughout the book are treated as part of the "story", and the solutions are on the very next page rather than in the back of the book or at the end of the chapter. As a result, the book is very easy to read, and flows extremely well. It feels much less like a textbook and more like a narrated lesson from an enjoyable professor.

With a topic as muddy and potentially confusing as regex, I was worried that the text would be just as confusing to follow. However, I was pleasantly surprised. The text itself is very well written, and very clear. There was never an instance in which I had trouble comprehending what the author was trying to communicate, and I almost never had to go back and re-read something multiple times to grasp the concept.

Furthermore, the text is full of excellent examples with accompanying explanations. The author almost exclusively teaches through example, and as a result, most of the lessons are extremely practical and great real-world applications. All of the code examples (of which there are many page-long instances of) are very well documented, and easy to understand.

Regex really is one of the most portable utilities that exists in the UNIX world. It can be applied to an enormous number of situations, and is interoperable with a laundry list of other tools and languages. As such, regex is not only a tool, but a general concept that must be grasped prior to proper usage - and this is what the first several chapters focus on. Thinking about problems in terms of regex is something that takes practice, and does not come easily to most people. This book tends to teach through example, and jumps right into matching simple regex to text lines to demonstrate how regex works. This brings me to my next point.

This book is not for beginners. I cannot stress this enough. The chapters not specifically aimed at a language require solid knowledge of a structured language like C++ or Java. Granted, the book really won't appeal to anyone that doesn't use computers on an advanced level on a regular basis; however, what I want to stress is that regardless of the reader's level of computer experience, if the reader does not have advanced knowledge of text handling in serious computer languages, most of the book's content will be too complex.

On the same note, and this is not a bad thing, about half the book is language-specific. There is a chapter for Perl, PHP, and Java. Obviously, if you don't know these languages, then most of the content of these chapters will be useless. This is not to say that the book will be useless to you if you don't know these languages - the non-language specific chapters occupy a large portion of the book, and contain more than enough material to master regex - however, the reader should be aware that just under half the book is aimed at specific languages.

Overall, this book is nothing short of fantastic. The audience for it is very limited - however, the author manages to make a concept difficult to understand, and even harder to master, easy to read about and learn. Clearly, a lot of thought went into the craft and design of this book, and it shows. I would highly recommend this book to any programmer, system administrator, or computer power user.

Very nice, good explanations.
Not exactly a plain old reference type book.

Incredibly well written and thought out, Mastering Regular Expressions explains both the syntax and philosophy behind regular expressions. You'll find that it is throughly researched, every nuance of a given regex implementation of the four featured languages (Perl, Java, ASP and PHP) is covered in extraordinary detail, containing information available NO WHERE online.

I bought this book after tooling around with regular expressions for a year or so and having limited success, my training having been limited to short online tutorials. After reading Friedl's guide, I have become much better at CORRECTLY programming regular expressions and "thinking regular expressions", that is, changing my outlook on a given task in order to apply regular expressions. I would highly recommend this book to anyone who deals with textual data on a daily basis, including, programmers, web developers and writers of any type.

I don't know about you, but in over 20 years of Unix use and work, I've always had a "problem" with regex. Yes, regular expressions are ANYTHING but "regular!" ...except that the notion extends to parsing text for patterns that are common.

Using regular expressions has always been a hurdle for me. I mean, you HAVE to be able to manage them at least a little in order to be proficient with Unix, but Mastering them, that's another story entirely. Jeff's (if I may call him Jeff) book is stellar. It reads easily and provides meaningful topics on using regex to your advantage.

I can't say enough about how well put-together this book is for the average person. Every topic is clearly visited and the discussion is pleasantly light and, at the same time, technically concise so as to provide real, useful help to using regular expressions. Here is an example:

"Mimicking atomic grouping with positive lookahead"

I consider this book to be a "brain dump" by perhaps the most accomplished regex guy in the industry. In the best of O'Reilly traditions, the book is very well laid out and presented. The quality of editing and "fit-n-finish" of the book are representative of this 3rd Edition.

If you encounter Regular Expressions in your work or as a hobbyist, this book shines a light into the darkness that opens the world of regex to you. It has been very practical and useful for me and it has really helped me be a much better regexer!

If you have ever been frustrated trying to figure out Regular Expressions (RegEx) based only on a table showing symbols and a few paragraphs of explanations obviously written by someone who assumes you are already familiar with the concept, then this book is for you. Don't be daunted by 480+ page size of this title; before you reach the end of chapter 2 you find yourself with a solid understanding of the concepts, structure, syntax and "keywords" in common use by those utilities, programming languages and applications that incorporate RegExs. The middle of the book covers implementation of RegEx in different environments, techniques for creating the expressions, and methods for creating efficient expressions. The end chapters are specific for Perl, Java, VB.NET and PHP users.

The only minor issues I had was in the tools used to demonstrate the concepts. Although no tool used cost the reader money if they wish to hands-on follow along, some of the downloads are from third-party sites which have no guarantee of offering the download by the time you get the book. Additionally, the author makes heavy use of Perl to demonstrate RegEx in scripting, which is fine for Perl users, but those that use other languages to fend for themselves. Seeing additional examples in other free languages, such as VBScript or JScript would have been nice.

Overall, Mastering Regular Expressions is an excellent choice for both learning the basics as well as better preparing yourself to apply them in real-world situations. The writing style is easy to understand and follow, and the layout allows this book to be a learning resource now, and a decent general reference later.

This book is an invaluable resource. I learned more than I wanted to know about regex after reading this book. The authors breaks things down to the smallest detail and discusses each aspect. He covers regular expressions, their engines, their use, and some tips and tricks without losing the reader.

If you are just learning regex, I don't recommend this book - but if you know a little and want to take your regex to the next step, this is the book for you!

I've corresponded personally with Jeffrey Friedl several times over the last few years, and I remember being at once impressed with his attention to detail and his focus. I was invited to be one of the technical review editors for this third edition of his authoritative book on Regular Expressions, but had to pass due to time constraints.

However, I am pleased to state that whoever the tech reviewers were, they did a thorough job on this one from O'Reilly. This book has matured over these three editions to become what I would consider the most detailed and valuable book about Regex on the planet - and that means whatever your favorite programming language or platform is.

You see, Regular Expressions is in itself a language, and transcends programming languages and platforms because the concepts are basically the same across all languages - whether it be Perl, JAVA, C#, Visual Basic, Javascript, PHP, Ruby, Python, TCL - you name it.

And this book focuses on the mastery of regex, not being a reference tool. Though each language has a different syntax for handling objects and methods, the underlying objects and methods are the same with Regex, so even complex examples shown in one language directly translate to the other languages.

Suffice to say that there are basic concept chapters that are really language - agnostic, and then specific sections on PHP, .NET, JAVA, and Perl. The book covers practical Regex techniques and most importantly, it gets you to the conceptual level where you can begin constructing Regex patterns on your own, without having to look for "examples".

For .NET developers, Jeffrey provides a complete table-based overview of .NET's Regular Expression flavor, with a focus on the new features available in .NET 2.0, including class subtraction, RegexOptions, and named capture.

In sum, let me just say that any developer who finds the need to manipulate text - whether it be scraping a web page, creating a report, importing data, or a hundred other applications, is going to need Regular Expressions. Jeffrey's book provides a complete and mature approach that is fresh, timely and detailed. I would recommend this book for any developer.

§
The third edition just came out -- and that makes 10 years since this book was first published. That statistic alone indicates the steady value of "Mastering Regular Expressions" across the constant changes in applied software technology over that time. Regular expressions, still the most under-used power tool, needs a book like this.

Specifically, this third edition features enhanced coverage of PHP in the early tutorial chapters, plus an all new chapter devoted entirely to PHP regular expressions.

Also new in this edition, the Java chapter has been rewritten and expanded to reflect new features as Java itself has developed.
§

Regular Expressions are a powerful pattern matching process built into many programming languages (but often hidden and not fully exploited).

If you are verifying input from a form or analyzing an HTML page or engaged in any other sort of pattern matching, Regular Expressions are something you should master.

The problems addressed by this book are (a) regex is poorly documented in general and (b) it has grown up ad hoc: every language's implementation is different from every other, sometimes very different.

The book does a good job of documentation and explanation in the early chapters. But in the later chapters it falls prey to the problem it is trying to solve. If you use Perl or Java or VB.NET, then this book gives a lot of very important information not easily found elsewhere.

On the other hand, if you use PHP, MySQL or JavaScript (as I do) you have to look elsewhere for the advanced topics.

Get the small pocket reference guide instead of this book! It is difficult to find what you want if you don't know exactly what you are looking for. I admit it covers the subject very well, but if you don't know Regular Expressions thoroughly, you have to read every word of the book or look forever to find what you want. Just buy the pocket reference guide and go to the library once a year when you need this thing.

The only book to explain regular expression in a clear and exhaustive manner, covering differences between the most important programming language in which regex are used.

A "must have".

I have known about regular expressions for a long time, but they have always been some kind of mysterious secret code. Recently I was reading something else that pointed out the power of regular expressions, so I decided it was time to learn regular expressions once and for all. After reviewing the available books on Amazon, I chose this one. I was not disappointed.

After reading just the first few chapters, I have been able to put them to work and make my life a lot easier. As a software engineer, I'm always doing searches through code or search/replace operations. I am now able to do more precise searches and do search/replace operations I never dreamed were possible before.

Learn regular expressions now! Get this book!

When first published in 1997, "Mastering Regular Expressions" was the only book with solid information on modern regular expressions, particularly as implemented in Perl 5. It quickly became a must-read book for anyone who wanted to learn more about regular expressions.

While the first edition had a heavy emphasis on Perl, the second edition of "Mastering Regular Expressions" (2002) equally covers Java and .NET

The first six chapters of the book (283 pages) deal with regular expressions in general. Don't expect an easy-going tutorial here. While you could read "Mastering Regular Expressions" without prior knowledge on the subject, the book is really intended for people who already know the basics, and are ready to get the most out of regular expressions. You'll get more out of the book if you read through the regular expression tutorial on this web site first to get some experience.

The book doesn't focus on teaching you how to use regular expressions at all, but how to use them efficiently. Expect lots of detailed information on how the regular expression engine works on the inside, and how to take advantage of this knowledge.

The final three chapters in this book each cover one of the three regex flavors that are probably the most widely used ones today. Chapter 7 covers Perl and its many regex-related features and tricks. Regular expressions are a core part of the Perl language, forming an essential part of almost any Perl script. Here you'll learn everything that no other book on Perl (that I know) will teach you. Where general books on programming in Perl usually have one chapter with a regular expression quick start, "Mastering Regular Expressions" shows you how to best use them with Perl.

The Java chapter consists of two parts. In the first part, the author compares various regular expression packages for Java. Since Java did not have any regular expression support built-in until version 1.4.0 of the JDK, there are many 3rd party packages available. If you're writing a Java app that needs to run on a Java VM prior to 1.4.0, the comparison certainly contains useful information. The last 20 pages of chapter 8 contain an introduction to the java.util.regex package that is part of the JDK 1.4.0 and later. If you're planning on using this package, you'll probably want to get a copy of "Java Regular Expressions" by Mehran Habibi to go along with "Mastering Regular Expressions".

The final chapter provides a good overview of the regular expression support in Microsoft's .NET framework, and how to best use it. This chapter provides a lot of information that is sorely lacking from the documentation included with the .NET SDK. While I wouldn't recommend buying this book just for the .NET chapter, "Mastering Regular Expressions" is certainly a good buy for .NET programmers wanting to get the most of their programming framework's excellent regular expression support.

Back in 2000 I had to complete some task and another engineer said "Use a Regular Expression". Ignorant of what a regular expression was, I got a quick explanation from the programmer who brought it up, and then I quickly got Perl to do what I needed, learning how powerful regular expressions are. Regular expressions are like that magical elixir, that wonderful little secret that was created to fix specific little problems, and man when you need them, they do the job better than almost any other.

If you are reading this review, you probably have some background as to what regular expressions are, but in a nutshell, they quickly let you find a particular search string and then modify it as needed. Regular expressions have their own ruleset as to how these searches/replacements are performed, and in order to learn how to write good RegExs, you need the book 'Mastering Regular Expressions'. You will not find a Regular Expression reference as good as this book by Jeffery Friedl, and I challenge you to look for yourself!

If you ever need to parse through a lot of data, whether it be logs or just finding a particular piece of code, you will save yourself a lot of time and gain much in performance by learning how to use Regular Expressions to accomplish the task(s) at hand. Having this book by your side will make that journey all the easier, and you will find lots of great examples pre-written, and new approaches as to how to write better RegExs to complete your tasks by having this text by your side. It's binary folks, if you use RegExs in your line of work, you need this book, you will not be let down!!

***** HIGHEST RECOMMENDATION

How come a technology that is as old as computers themselves is still around? Regular expressions solve one of the most basic problems in computer science: parsing strings.
There is no doubt that regular expressions are beasts. This will will demystify them. By understanding them, you will be less scared of using them. This book does just that. However, the level of this book is high and the level of details amazing. It is not a cook book so it would be wise to also read another book that gives you more examples. This particular book is like the bible of regex. It needs to be in your library.

If you are an experienced programmer, then you have undoubtedly heard of the power behind regular expressions. Unfortunately, even for seasoned developers, becoming very proficient in regular expressions is no trivial task... or is it? Sure most regular expressions look very arcane and are even harder to write, but luckily there is at least one good resource to help bend the learning curve. I am talking about Mastering Regular Expressions by Jeffrey Friedl. This book breaks down regex to such a trivial level that you can't help but learn how to harness the regex power. Jeff takes you step by step through regex land and holds your hand throughout the whole trip. Next thing you know, you will be crafting high quality regular expressions and you will learn how to truly harness such a powerful tool.

Unfortunately in every programmers life there are mental blocks that keep us from truly progressing. For some it's pointers or OOP concepts and for others such as myself its regular expressions. This book took that mental block and smashed it, then it paved the way to regex land. Now I feel much better! HIGHLY recommended!

Jeffrey Friedl is the man whom I credit for getting my start in computer programming. I even sent him a thank you letter after reading his first edition. Once you take the time to learn Regular Expressions, you'll often wonder how you got by without them. There is no better book to teach you than this one.

Plain and simple, this is the definitive work on regular expressions... Mastering Regular Expressions (2nd Edition) by Jeffrey E. F. Friedl (O'Reilly).

Chapter List: Introduction to Regular Expressions; Extended Introductory Examples; Overview of Regular Expression Features and Flavors; The Mechanics of Expression Processing; Practical Regex Techniques; Crafting an Efficient Expression; Perl; Java; .NET; Index

I've always been a bit reluctant, hesitant, perhaps even fearful to work with regular expressions. I mean, when you're presented with the following:

s!([0-9+(\.[0-9]+){3})!$1!

who wouldn't start to fear for their sanity?

I recently started to explore the subject a bit in the Notes/Domino arena, and I quickly realized I needed more information than I had. This book fills in all the gaps and then some. It's one of those rare books that starts at an introductory level, simple enough (given the subject matter) that beginners can start to grasp the concepts. If you're past the beginning stages, you can head into the chapters on how to write efficient expressions, as well as how arcane commands interact with each other. If you're not there yet, just keep the book around for reference when you do arrive. To finish the book off, there are chapters on specific implementations of regular expressions in certain languages. This ties the whole package together... introduction through advanced techniques, finished by focused information specific to a particular area of use. You can't ask for much more. It's also nice that the 2nd edition came out after Java had implemented the regex package in 1.4, so you get the latest information.

If you have a copy of this book, make sure your name is in it. This is not one of those titles you want to have turn up missing at the exact moment you need to figure out a nice single line statement to correct a 100 MB text file... Highly recommended.

Like the other Oriely books I've read, this book tells you everything you ever wanted to know about regex and probably a lot of stuff that is interesting but not practically nescary. This book covers regex egines and most common implimentation of regex. It's all good stuff but I would like a book that is more focussed on the practical details of this how you write a regex to validate a phone number or a data etc....

This is one of the few O'Reilly books that I read cover to cover. What? A book on regular expressions read cover to cover? If you have read the book, I suspect that you understand. If not, read it. Even a cursory skimming (if possible) will provide valuable information in HOW regular expressions work - the syntax, the underlying engine, differences in implementation. Highly recommended.

On a sidenote, the regular expression in the back of the book (a full page long) has been the topic of conversation in my workplace more than once. I suspect that it will eventually become one of those "geek indicators" like the number 42 or PARC.

Great book for newbies and advanced users alike. Regular Expressions are a pain to understand and learn, but this book is a great teaching tool for that. If you're interested in learning RE, this is the book to start with.

Mastering Regular Expressions is for many people including among others casual users, system administrators, and programmers. Only programmers will understand (or need) the whole book, but people with only a tiny little Perl or Unix knowledge will gain much from the first few chapters. The RegEx book is useful as a primer to go a little beyond the usual wild card (i.e. '*') when searching text files for something, it's useful for systems administrators who need to write task automation scripts, and it offers Perl, Java, and .NET programmers a complete reference to the RegEx engines they need to understand to optimize their code.

And if they don't already have it, this will make a great present for your techno geek other half. They'll be impressed...

If I could give this book 10 stars I would.

This book opened my eyes to a lot of possibilities with regular expressions that I never knew existed. I had heard of regex programming for years, but had no idea they could be so powerful.

I don't know what else to say that hasn't already been said in other reviews. If you want or need to learn regular expressions, this is the *only* book you will need to buy.

One of the hardest things, even for a seasoned programmer to grasp is regular expressions. They are powerful ways to search, manipulate and parse text fields and can often take several lines of code and shrink it down to a mystic, but powerful, expression.

If you have ever had to parse a file for information, you know that one of the things that still haunts any programmer nowadays is how to match text. In this day and age of Object Oriented Programming, Web Services, etc. the power of Regex holds firm.

Throughout this book the author takes great care not to overwhelm the reader with tons of code that has no meaning. The power of the book comes from the fact that if you read, and follow along, through the examples you will gain an understanding of how to do the techniques the author is referring to. At times it may seem like you have to read over a section twice, but you will realize that as you carry forth into the next section the material you read previously has turned into something you can now apply -- not just another example you can cut and paste and never really learn technique behind.

This is a powerful book, covering many, many pages. Noone should expect to sit down and read it cover to cover and be done with it. The benefit comes from reading, applying, and referencing. I find myself using it several times a week to lookup information on Regular Expressions and to held solidify knowledge of techniques that I have used in the past.

Whether you are a Windows, Unix, or even Macintosh person -- RegEx holds the key to text manipulation -- and this book holds the map you need to find that key.

Regular expressions always terrified me. I really got tired of looking for related examples on the 'net and hacking sample code so I decided I had to take the plunge.

I can say that the first chapter of this book is one of the most important chapters of any book I ever read. It leaves you breathless. Actually you'll probably want to read it again as the first time round you were so glued to the pages you didn't have time to try out the examples yourself.

In a book such as this layout and typographical conventions are of utmost importance and this book gets this spot on. An author who can cover this subject without simply using masses of examples and dry outlines of selected syntax arrangements deserves an acolade. This book goes further. It stimulates the juices and is a struggle to put down (to the detriment of your hands-on practice as mentioned above).

I was quite wary of exploring the territory of regular expressions and used to be very ambivalent towards Perl but this book helped to ease me in to a whole new world of script programming.

This book is not just for Perl geeks. PCREs (Perl Compatible Regular Expressions) are creeping into other programming and scripting languages now and this book will serve you no matter where you're coming from.

Get this book and get over your fear!

This is a great guide to regular expressions in Perl. It's so nice to see a 'proper' book once in a while, instead of superficial dumbed-down crap.

I had just started learning perl and I knew I needed to learn how to use regular expressions. I breezed through learning perl and this book was next.

I knew very little about regular expressions before reading this book and now I feel like I've mostly mastered them. I've read through it once and there is a lot of material that it covers so it was difficult to comprehend all of it the first time through but I feel I've understood the majority of regular expressions. I think the only part I would need to read through more is the optimization of regular expressions.

I used, but never truly understood, regular expressions until I read this book. If you use regular expressions in a production setting you need to understand them at a deep level to make sure you won't fall into performance traps. This book provides that deep perspective. The author really knows his stuff and is able to communicate it effectively. Another O'Reilly classic.

I have struggled with regular expressions for a couple of years now. Like most people, I knew 'something about them', and could cobble together a simple regex. But when it came to more demanding searches, I had to find the regex on the web, or I was out of luck.

This book guided me to the next level (at least). It is one of the better computer tutorials I have read in the past couple of years. If you are looking for a resource to learn regular expressions, this is the one I'd recommend.

While the various websites give a lot of good information on regular expressions, they don't show enough about building them from scratch. This book does a great job of laying a good foundation and then helping the reader understand how to build expressions from there.

If you want to learn the ins and outs of how a regular expression really works, this book does a great job explaining all the syntax, intricacies, optimization, greedy match, and non-greedy match. I highly recommended for those who writes a lot of regular expression.