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.

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!

Well written, informative, and surprisingly accessible. I have some great new tools to do my work efficiently.

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.

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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.
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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.