# regular expressions

(60 minutes to learn)

## Summary

A regular expression is a sequence of characters describing a pattern against which strings can be matched. They are commonly used to search text files for patterns, e.g. as in tools like grep.

## Context

-this concept has no prerequisites-

## Goals

- Be familiar with regular expression syntax

- Be able to write regular expressions to solve simple problems

## Core resources (read/watch one of the following)

## -Free-

→ Coursera: Automata

An introductory course on automata and the theory of computation.

## -Paid-

→ Automata Theory, Languages, and Computation

An undergraduate textbook on automata and the theory of computation.

- Section 3.1, "Regular expressions," pages 85-92
- Section 3.3, "Applications of regular expressions," pages 109-115

## Supplemental resources (the following are optional, but you may find them useful)

## -Paid-

→ Introduction to the Theory of Computation

An undergraduate textbook on automata and the theory of computation.

Location:
Section 1.3, subsection "Formal definition of a regular expression," pages 64-66

## See also

-No Additional Notes-