Practice Makes Regexp — just the book by Reuven M. Lerner

Practice Makes Regexp — just the book

Stop fiddling with regular expressions, and start mastering them


Have you ever known a developer who needed to use a regexp to solve a crucial, time-boxed problem, at work? They know that you can get it…if they just add parentheses here. Or a plus sign there. Or a question mark at the end. Or something.

They spend hours fiddling—trying to figure out the proper syntax and searching online and plugging in snippets that may or may not work.

It’s a tedious and time consuming system, and even worse, guarantees that their regexp won’t quite do what they want. No wonder so many people give up before they master regular expressions!

Stop fiddling, and get back to coding

Some developers try to learn regexps via books and websites. But most of those resources just throw some syntax at you, and tell you that you’ll be set. I know from experience that this system doesn’t work (both from when I started to program, to more than a decade of teaching regexps at major high-tech companies around the world). Just as reading a single grammar book won’t teach students a foreign language, developers can’t learn regular expressions from memorizing the syntax alone.

So, how do developers master regexps? They treat it as a language—and then practice, practice, practice.

Once you do practice them, you start to internalize their structure and power. And then you start to see more and more places in which regexps can solve problems, more quickly than you ever imagined.

You can get your own work done faster because you have the right tools to attack the problem, and you line yourself up for good things, like promotions and tackling that side project application you always dreamed of creating.

Get your coding time back

Practice Makes Regexp doesn’t aim to teach developers regular expressions.There are other books and resources for that.

Rather, this course aims to take a fledgling knowledge of regexps, and make regexps fluent and natural! 

Here’s what you get:
  • 50 regexp exercises, solutions, and explanations
  • all in a 175 page ebook
  • With solutions for Python, Ruby, JavaScript, and PostgreSQL

Each exercise in Practice Makes Regexp has solutions in Python, Ruby, JavaScript, and PostgreSQL (except for the chapter on the Unix shell, in which solutions are presented for the “grep” command).  No matter which of these languages you use, this course will help you to do your work faster and better, working fluidly with text and extracting precisely what you need. If you have been struggling to use regular expressions in your work, then I believe Practice Makes Regexp is the course that you’ve been waiting for.

Not sure if the book is for you? Or do you need a refresher course in regular expressions?  You can sign up for my "regular expressions crash course," at .

What's included?

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Become a better developer.

I'm Reuven — and for 20 years, I've spent just about every day teaching Python, data science, and Git at some of the world's best-known companies. 

I've recorded my most popular courses here, for you to learn these skills — even if you don't work for a big company.

After taking my courses, you'll be able to to solve bigger problems in less time — allowing you to do your current job better, or to find a new, better job.


What if I dislike the course?

If you don't think you're getting value from Practice Makes Regexp, then ask for a refund, and I'll give you one.

Will this book teach me regular expressions?

No, at least not directly. The idea is that you have some basic background and understanding of regexps, and that you want to identify and improve the areas of weaker understanding. The explanations that accompany each solution are designed to remind you of functionality that you might not remember, or techniques that you can (should) use.

The book includes a chapter that describes the different types of regular expression syntax out there, and where you can go to get additional help, including Web sites that can help you debug regexp issues.