This book is the best regular expression book out there. I've been writing software for several years and my practical experience didn't scratch the surface of what regular expressions can do and how they work.

If you want to decipher complex regular expressions and write your own, this is THE book to read. Friedl never glosses over important points and he never makes assumptions that you already understand regular expressions. The fact is, most of us just don't. Although regular expressions is mostly a pretty dry topic, Friedl does a good job lightening things up here and there (enough to prevent the topic from being too dry, but not so much that we forget the serious nature of the subject matter).

The typographic conventions are nothing short of groundbreaking, and I believe there is no other volume out there, on the web, or written that does as good of a job walking you through regular expressions, explaining how all the various parts work together and how to do things in your own practical way.

This book teaches you to THINK in regular expressions. Those once cryptic symbols will become powerful tools for you to manipulate and get the results you need. For me, regular expressions were a bit of stumbling block and a possible security risk (since I couldn't decipher really complex regular expressions). Aside from that, I didn't know the difference between NFA, DFA, and Posix NVA or how to optimize regex for these various engines (or whether optimization is even needed).

I strongly recommend this book for both beginners and veterans of regular expressions. It might not change your life, but it will change the way you read and write regular expressions.

Most regex books, blogs, websites, tutorials and classes cover “just the basics” really. Even the ones that say “advanced” often barely get into lookarounds.

This book is the definitive guide on regex. Full stop. I’m not quite halfway through and it has already increased my understanding of regex in ways I hadn’t imagined possible. That said, the 3rd edition is 16 years old and it shows. The author regularly references now out-of-date technologies (e.g., PHP and Tcl). But that in no way hampers his ability to teach and ingrain the material. One just simply needs to understand that due to its age, some claims may no longer be true.

For example, (and bare in mind I’m halfway through so I don’t know what I don’t yet know) there’s a chart stating that MySQL’s regex engine is a DFA. From what I’ve read, and knowing that MySQL “upgraded” their regex support in version 8, I believe it may now be an NFA. Or, at the very least, a hybrid. I could be wrong, but the point is, before reading this book, I wouldn’t have understood enough to even make that guess.

Now, will I skip the chapters that focus on PHP and Tcl? Perhaps the latter. It’s not like I can’t come back and read it later if I find myself ankle-deep in Tcl regex one day. I could say the same for PHP, but it’s in a lot of legacy software, so a quick read through it is probably worthwhile.

Not to keep bringing it up, but even halfway through, my understanding of lookarounds increased substantially. I use all of them regularly, but with a half-understanding of what was going on or why it would work sometimes and others not. Beyond that, greedy/lazy/possessive quantifiers… grouping. Sure, I’ve used them at some point. Some more often than others and with more understanding. But now? I get it all.

It’s kind of a shame. I don’t have to write regex every day and when I do, it’s usually file searching, so it’s throw-away code. However, I haven’t yet read the chapters on efficiency, so perhaps my knowledge will grow in that area and that will pay off daily!

Anyway, if you have any regular use of regex, this book is worth it. I picked up a used copy. I’d have paid cover price ($44.99 USD) easily knowing what’s actually in the book, how it’s written, etc. That brings me to my final point. The author does an amazing job of keeping what could be a very dry subject fresh and clear. You just can’t appreciate that enough.

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.

I use to google "regex" and refer to the websites that would show from the search results. In my opinion, most of these sites were hard to use when trying to really understand regex. Maybe I wasn't persistent enough to screen crawl through several regex webpages/websites. I knew in my very soul I didn't understand regex well, because of constant issues coming up with seemingly easy regular expressions. I finally decided I wanted something comprehensive to learn regex.

This book gave me the level of understanding I was looking for. After reading this book I can confidently say that I'm 1000% more comfortable reading and creating my own regex. I stopped once I reached chapter 7 because the last chapters, 7-10 are language specific chapters, but in the future I'll definitely refer back to those chapters once I'm working with those languages.

Lastly, I did get some flak from other devs while I was reading this book "Geez you're reading a book on regex?? wow that's too boring for me." etc. etc. Don't listen to the haters! If you want a greater understanding of regex, and this book can get you there then don't listen to those nerds. At the end of the day and with learning anything, it only matters that the nerd in your shoes understands the subject. Also, take your time reading the book. It's perfectly fine to pace yourself and take more time reading, because there's a lot of needed detail.

I'm working on the PCAP, but I know a little about programming languages, and somewhere I picked up noun phrases and verb phrases.

If you want to have a deeper understand of regular expressions then this is a good book for you. If you just want a regular expression cookbook then this book is definitely not for you. It's written in a story form and it builds upon itself so unless you are willing to read it linearly then you would be wasting your time. It talks a lot about how different regular expression engines work and this is helpful to understand how to build regular expression.

This is one of the best books a person could imagine on a highly technical theme. The author keeps a wonderful balance of theory, practice, and those pesky details that really make all the difference when one sits down to complete a project.

By not asserting himself as a mathematical authority, Friedl lets his cleverness come through in a practical, 'human-to-human' way. There are a few moments when the more theoretically minded reader might want a little more detail, but the balance Friedl keeps is beyond admirable.

In the entire book there are perhaps only a half-dozen pages that are 'challenging' to the mind, yet by the time the reader has finished the book he or she will be amazed, simply amazed, at the complexity of regular expressions that can be interpretted with ease. Of course, writing expressions takes more practice, but the regex muscles won't even notice the feather-light daily tasks of, say, basic data validation after working out on this text.

The book will start the reader looking for possible regex solutions everywhere, and provides enough detail to take the fear out of using them.

Lots of good information, well organized, well presented.

My only complaint is the fonts. Both the text of the book and the source code. The font used for the regular text is very light, I would have preferred a larger, darker, and more bold font. The font used for the source code is absolutely horrible. There are little angle brackets used to identify a block (for example to highlight what has changed from the prior example). They are almost impossible to see. This is important because the author is constantly referring to the highlighted portions. Some pages are darker print than others, its inconsistent.

If another edition of this book is ever made, I would like to see larger more bold font, and use a completely different method to "highlight" portions of text in the code samples.

I wonder if this font issues occur in the Kindle edition...?

... para cualquier lenguaje de programación

日本語版の半額程度で購入できました。

英語の勉強にもなっていいかもしれません。

とは言うものの、まだ最初の方しか読めていませんが。

Very thorough, great reference, hard to just read from cover to cover but will get there eventually. Great price for second hand very good condition.

Ensina com maestria coisas que eu não sabia que não sabia. Não se limita a ensinar expressões regulares para o uso cotidiano; mostra também como as expressões são processadas e compara explicando a diferença de performance de diferentes patterns.

Yes, this book is from the mid-2000s. No, it’s not outdated. Mastering Regular Expressions is still the clearest, most in-depth way to learn regex—regardless you’re coding in Perl, Java, PHP, or building your own data-parsing. All - in - all, Regex feels like learning a new language: confusing at first, but over time, its secrets unfold and the patterns start to click.

This isn’t a quick-tip book—it’s a deep dive. If you’re serious about getting results (and not just reading the story), this will give you the skills to bend data to your will. Timeless, practical, and surprisingly addictive.