What is the function of regex in C#?

In C#, Regex (regular expression) is a class used for text matching and replacement. It can assist developers in performing advanced text processing operations such as searching, replacing, validating, and splitting.

In specific terms, the functions of Regex include the following aspects:

1. Pattern matching: Regex can match specific content in input text by using specific patterns. Developers can define matching rules using various metacharacters and pattern options to find the desired text.
2. Search and replace: Using regex, developers can search for specific patterns within a given text and perform replacement operations. They can use either a replacement string or a callback function to generate the replacement result.
3. Input validation: Regex can be used to check if user input meets specific formatting requirements. For example, Regex can be used to validate if email addresses, phone numbers, etc., are entered correctly.
4. Regex can divide a given text into multiple parts based on a specific pattern, which is very useful for dealing with complex text data and quickly obtaining the desired information.

Overall, Regex plays a powerful role as a text processing tool in C#, helping developers quickly and flexibly perform various text operations.