Commonly used RegEx for DotNet. Email, Password etc.

Constants.cs

public static class Constants
{
  public static class RegEx
  {
    public const string Email = @"^[a-zA-Z0-9#'$%+/=?^_`{|}~-]+(?:\.[a-zA-Z0-9#'$%+/=?^_`{|}~-]+)*[a-zA-Z0-9#'$%+/=?^_`{|}~-]*@(?:[a-zA-Z0-9](?:[a-zA-Z0-9-]*[a-zA-Z0-9])?\.)+[a-zA-Z0-9]{2,}$";
    
    // Passwords must be at least 8 characters and contain at 3 of 4 of the following: upper case (A-Z), lower case (a-z), number (0-9) and special character (e.g. !@#$%^&*)
    public const string Password = "^((?=.*?[A-Z])(?=.*?[a-z])(?=.*?[0-9])|(?=.*?[A-Z])(?=.*?[a-z])(?=.*?[^a-zA-Z0-9])|(?=.*?[A-Z])(?=.*?[0-9])(?=.*?[^a-zA-Z0-9])|(?=.*?[a-z])(?=.*?[0-9])(?=.*?[^a-zA-Z0-9])).{8,}$";
  }
}