Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Good Little Reference Book

A good reference book for Regular Expressions. No one is going to learn regular expressions from this book. It does have an introduction to regular expressions, but that's all. The book's strength is that it covers several implementations of regular expressions, including Perl, Java, .NET/C#, PHP, Python, Ruby, and JavaScript.If you want to learn regular expressions, find another book. Several reviewers have suggest good books for learn all about regular expressions.On the other hand, if you want a quick, easy reference tool, this is the book. If you understand regular expressions and just need a reminder on how a certain language implements it, then this it the right book.