using System.Text.RegularExpressions; namespace Algorithms.IdCard; public class PostalCode { private string postalCode; public PostalCode(string postalCode) { this.postalCode = postalCode; } public bool IsValid(){ Regex rx = new Regex(@"^[A-Z]\d[A-Z] \d[A-Z]\d$"); return rx.Match(this.postalCode).Success; } }