Common patterns and character classes in Ruby

Introduction

We use common patterns and character classes to find or check specific types of characters in text easily.

Checking if a password has letters and numbers.

Finding all digits in a phone number.

Extracting words from a sentence.

Validating if an email address has the right characters.

Syntax

Ruby

/[pattern]/

Patterns go inside slashes / / in Ruby.

Character classes like \d or \w match groups of characters.

Examples

Matches any single digit (0-9).

Ruby

/\d/

Matches one or more word characters (letters, digits, or underscore).

Ruby

/\w+/

Matches any single vowel letter.

Ruby

/[aeiou]/

Matches any character that is NOT a digit.

Ruby

/[^0-9]/

Sample Program

This program looks inside the text "Hello123" to find digits and words using common patterns.

Ruby

text = "Hello123"

puts "Digits found:"
text.scan(/\d/).each { |d| puts d }

puts "Words found:"
text.scan(/\w+/).each { |w| puts w }

Important Notes

Use double backslashes \\ in Ruby strings to write special patterns like \d.

Character classes help you avoid writing many separate characters.

Square brackets [] define a set of characters to match.

Summary

Common patterns help find specific characters in text.

Character classes like \d and \w match digits and words.

Use these patterns inside slashes / / in Ruby.