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Build your own grep

Learn about regex syntax: character classes, quantifiers and more

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This challenge is free until 1 October 2024!

Regular expressions (Regexes, for short) are patterns used to match character combinations in strings. In this challenge you'll build your own implementation of grep, a CLI tool for searching using Regexes.

Along the way you'll learn about Regex syntax, character classes, quantifiers and more.

Stages

Match a literal character
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Match digits
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Match alphanumeric characters
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Positive Character Groups
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Negative Character Groups
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Combining Character Classes
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Start of string anchor
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End of string anchor
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Match one or more times
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Match zero or one times
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Wildcard
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Alternation
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Backreferences

Single Backreference
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Multiple Backreferences
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Nested Backreferences
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