The reg-ex activities make it possible to do advanced search and replace actions on strings
More about the options available in reg-ex: Options
Regex examples:
1.Email validation: ^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$
2.Date in YYYY-MM-DD format: ^\d{4}-\d{2}-\d{2}$
3.IP address validation: ^((25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)$
4.URL validation: ^(https?:\/\/)?([\da-z\.-]+)\.([a-z\.]{2,6})([\/\w \.-]*)*\/?$
5.Extracting file extension: \.[0-9a-z]+$
