Feeds

Mastering Regular Expressions

Not just a text book – a real guide

  • alert
  • submit to reddit

Combat fraud and increase customer satisfaction

Book review Like SQL and XML, regular expressions are an essential tool in every developers’ toolbox. Processing text, which is pretty much what most programs do when you think about it, is so central a concern that even without regular expressions most developers quickly build up a library of functions and idioms for text matching, replacement, parsing, token extraction etc.

Regular expressions go a whole lot further and are, in effect, a specialised language for text processing in all its messy glory. The downside to this extra power is that it comes at a price – regular expressions have a reputation for being difficult to craft, difficult to debug and difficult to read. No wonder that regular expressions are often seen as the preserve of obscurantist hackers who make a virtue of impossible-to-decipher Perl one-liners.

Jeffrey Friedl’s Mastering Regular Expressions, now into a thirdedition, is something of a classic of its kind. The aim is simple enough – to make regular expressions your friend. No matter what your platform or programming language of choice, Friedl’s book is designed not just to get you started, but to set you well on the way to expertise.

The key to achieving this mastery is to provide plenty of examples throughout the entire 500+ pages of text. From the word go the emphasis is on real examples, building each one up in complexity to match the kind of problems that occur with real text rather than the sanitised kind that only seems to exist in text books. Want to strip out IP addresses or URLs? What might appear to be a straightforward case ends up being tricky and complicated – but along the way Freidl points out the kinds of problems that will bite you if you’re not careful. He also repeatedly makes the point that there’s a trade-off between completeness, performance and the state of the data you’re dealing with.

The first six chapters are devoted to general topics – providing plenty of extended examples, discussion of different flavours of regular expression engines, some history, coverage of efficiency issues and so on. These six chapters include material on regular expression support in Perl, Java, Python, Ruby, C# and VB.NET, PHP as well as tools like egrep, awk and so on.

The final four chapters of the book are devoted to regular expression support in specific languages and platforms: Perl, Java, .NET and PHP. In each case there is a combination of more worked examples and detailed discussion based on the material covered in the first six chapters. For developers using any of these languages this material is a bonus that consolidates the core understanding that Friedl establishes in the earlier sections of the book.

As well as the clear writing style, the book also scores well in terms of overall design. The typography stands out in terms of clarity when displaying regular expressions and the text that it matches – it’s always clear what’s what, with the different components clearly marked out. Another good design feature is that the questions Friedl poses the reader always have a solution on the next page – you don’t ever see the answer before you’ve had a chance to ponder the question, and neither do you have to flick to the end of the book. It makes answering the questions a more natural part of the reading process.

Mastering Regular Expressions

Verdict: Highly recommended to anyone wanting to really get to grips with regular expressions.

Author: Jeffrey Friedl

Publisher: O’Reilly & Associates

ISBN:0596528124

Media: Book

List Price: £31.99

Buy this book at Register Books at Reg Developer's special discounted price!

Combat fraud and increase customer satisfaction

More from The Register

next story
OpenBSD founder wants to bin buggy OpenSSL library, launches fork
One Heartbleed vuln was too many for Theo de Raadt
Got Windows 8.1 Update yet? Get ready for YET ANOTHER ONE – rumor
Leaker claims big release due this fall as Microsoft herds us into the CLOUD
This time it's 'Personal': new Office 365 sub covers just two devices
Redmond also brings Office into Google's back yard
Ubuntu 14.04 LTS: Great changes, but sssh don't mention the...
Why HELLO Amazon! You weren't here last time
Patch iOS, OS X now: PDFs, JPEGs, URLs, web pages can pwn your kit
Plus: iThings and desktops at risk of NEW SSL attack flaw
Next Windows obsolescence panic is 450 days from … NOW!
The clock is ticking louder for Windows Server 2003 R2 users
Batten down the hatches, Ubuntu 14.04 LTS due in TWO DAYS
Admins dab straining server brows in advance of Trusty Tahr's long-term support landing
Red Hat to ship RHEL 7 release candidate with a taste of container tech
Grab 'near-final' version of next Enterprise Linux next week
Apple inaugurates free OS X beta program for world+dog
Prerelease software now open to anyone, not just developers – as long as you keep quiet
prev story

Whitepapers

Mobile application security study
Download this report to see the alarming realities regarding the sheer number of applications vulnerable to attack, as well as the most common and easily addressable vulnerability errors.
3 Big data security analytics techniques
Applying these Big Data security analytics techniques can help you make your business safer by detecting attacks early, before significant damage is done.
The benefits of software based PBX
Why you should break free from your proprietary PBX and how to leverage your existing server hardware.
Securing web applications made simple and scalable
In this whitepaper learn how automated security testing can provide a simple and scalable way to protect your web applications.
Combat fraud and increase customer satisfaction
Based on their experience using HP ArcSight Enterprise Security Manager for IT security operations, Finansbank moved to HP ArcSight ESM for fraud management.