If you have a question about RegEx this is the book with the answers. RegEx: Questions and Answers takes some of the best questions and answers asked on the stackoverflow.com website. You can use this book to look up commonly asked questions, browse questions on a particular topic, compare answers to common topics, check out the original source and much more. This book has been designed to be very easy to use, with many internal links set up that makes browsing in many different ways possible. Topics covered include: Java, JavaScript, PHP, Python, C#, Ruby, validation, split, PCRE, parsing, escaping and many more.