Topic 2. Regular expressions and text processing in C#

Goal: become familiar with .NET regular expression syntax and the classes of the System.Text.RegularExpressions namespace; learn to validate, search, extract, replace, and split text data using the Regex class, groups, lookarounds, and RegexOptions; master protection against catastrophic backtracking, the [GeneratedRegex] source generator, and unit testing of patterns.

Lecture contents

1. Regular expression syntax — Regular expressions in .NET · Characters and character classes · Quantifiers, anchors, and alternation
2. The Regex class and groups — The Regex class and match results · Groups and backreferences
3. Replacement, options, and lookarounds — Replacing and splitting text · RegexOptions · Lookahead and lookbehind
4. Performance, generation, and testing — Performance and security · The [GeneratedRegex] source generator · Input validation and unit tests for patterns
5. Common mistakes — Common mistakes

Practice and review

• Practice — 3 worked examples with complete code and output
• Tasks — 30 variants, each with tasks at three difficulty levels
• Summary — conclusions, self-check questions, and useful links