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created: 02/04/10, revised: 08/14/2016

CHAPTER 9 — Regular Expressions III

This chapter discusses features of regular expressions (as implemented in Java classes) that go beyond the basic features of the last two chapters. Some of these features go beyond the strict mathematical definition of a regular expression, and thus the languages they recognize are sometimes not regular languages. However, these features are very useful for programming.

Sometimes the word regex is used for an expression that has features not allowed in strict regular expressions. However, these chapters continue to use "regular expression" for all expressions.

Chapter Topics:

Many programming languages and text editors use regular expressions. However, the syntax of this chapter is for Java regular expressions and may not work for other applications. (However, the basic syntax of Java regular expressions will work in most other applications.)



What strings are matched by   [0-9]*     ?

What strings are matched by   [^0-9]*     ?