Gain insights into pattern matching with regular expressions in C#. Explore data validation, information extraction, and more using String and Regex APIs with practical examples.

Regular expressions provide an extremely powerful method for pattern matching with strings. They are very useful for parsing information like dates, phone numbers, or zip codes from important text files, such as code files, log files, spreadsheets, or documents. The course discusses everyday use cases of regular expressions, e.g., data validation, information extraction, pattern matching, and search and replace.

This course will teach you the core concepts of pattern matching, character classes, special and meta characters, and quantifiers. You will also learn conditional regular expressions including lookahead and lookbehind assertions. You will also learn the APIs used in C# for regular expressions with hands-on code widgets. 

This course will teach you how to perform pattern matching with a regular expression using String and Regex APIs for the above-mentioned practical use cases in C#.

Tarun Telang

Tarun Telang is a passionate software engineer, leader, architect, author, and active contributor in various online technical forums.

C# and Microsoft Expert

Working with Regular Expressions in C#

**Backreferences** allow us to reuse previously matched sub-strings within a regular expression pattern. A backreference matches the same sub-string that a capture group already matches.

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## Using `\\n` for backreferencing

To create a backreference, we use the following syntax:

```txt
\\n
```
Here, `n` is the index of the captured group.

The following code shows how to match a date in the `mm/dd/yyyy` format and then reformat it to `dd-mm-yyyy`:

Learn how to use back references for processing inputs having more than one match.

Introduction

Building Blocks of .NET Regular Expressions

Advanced Concepts

Course Wrap Up

Working with Backreferences

Backreferences

Using `\\n` for backreferencing

Working with Backreferences

Backreferences

Using \\n for backreferencing

Using `\\n` for backreferencing