C# class for simple checking of birth number validity with some useful parameters. C# třída pro práci a validaci rodného čísla s pár užitečnými parametry.

BirthNumber.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Text.RegularExpressions;
using System.Runtime.Serialization;

namespace net.mishak.utils
{
    class BirthNumber
    {

        public string Suffix
        {
            get;
            private set;
        }

        public string YearMonthDay
        {
            get;
            private set;
        }

        public string Text
        {
            get
            {
                return YearMonthDay + "/" + Suffix;
            }
        }

        public int Year
        {
            get
            {
                int year = Convert.ToInt16(YearMonthDay.Substring(0, 2));
                /* @TODO revisit in 2054 */
                return year + (year < 54 ? 2000 : 1900);
            }
        }

        public int Month
        {
            get
            {
                int month = Convert.ToInt16(YearMonthDay.Substring(2, 2));
                if (month > 70) /* adjustment for females per 53/2004 */
                {
                    month -= 70;
                }
                else if (month > 50) /* adjust for females */
                {
                    month -= 50;
                }
                else if (month > 20) /* adjustment for males per 53/2004 */
                {
                    month -= 20;
                }
                return month;
            }
        }

        public int Day
        {
            get
            {
                return Convert.ToInt16(YearMonthDay.Substring(4, 2));
            }
        }

        public enum BirthNumberSex
        {
            FEMALE,
            MALE
        }

        public BirthNumberSex Sex
        {
            get
            {
                return Month > 50 ? BirthNumberSex.FEMALE : BirthNumberSex.MALE;
            }
        }

        public DateTime Date
        {
            get
            {
                return new DateTime(Year, Month, Day);
            }
        }

        private BirthNumber(string yearMonthDay, string suffix)
        {
            YearMonthDay = yearMonthDay;
            Suffix = suffix;
            CheckChecksum();
            CheckDate();
        }

        private void CheckChecksum()
        {
            // birth number is padded with last digit to be divisible by 11
            if (Convert.ToInt16(YearMonthDay + Suffix) % 11 != 0
            // only exception is if remainder of first nine numbers divided by 11 is equal to 10 then it is padded with 0 and is not divisible by 11
            && !(Suffix.Length == 4 && Suffix.Substring(3, 1) == "0" && Convert.ToInt16(YearMonthDay + Suffix.Substring(0, 3)) % 11 == 10))
            {
                throw new InvalidBirthNumberException("Checksum is not matching.");
            }
        }

        private void CheckDate()
        {
            try
            {
                DateTime dateTime = Date;
            }
            catch (ArgumentOutOfRangeException)
            {
                throw new InvalidBirthNumberException("Date is not valid.");
            }
        }

        public static BirthNumber FromString(string s)
        {
            Regex reg = new Regex("^([0-9]{6})/?([0-9]{3,4})$");
            Match match = reg.Match(s);
            if (!match.Success)
            {
                throw new InvalidBirthNumberException("Invalid format");
            }

            return new BirthNumber(match.Groups[0].Value, match.Groups[4].Value);
        }

        public DateTime GetDate()
        {
            return new DateTime(Year, Month, Day);
        }
    }

    class InvalidBirthNumberException : Exception, ISerializable
    {
        public InvalidBirthNumberException()
            : base()
        {

        }

        public InvalidBirthNumberException(string message)
            : base(message)
        {

        }

        public InvalidBirthNumberException(string message, Exception inner)
            : base(message, inner)
        {

        }

        protected InvalidBirthNumberException(SerializationInfo info, StreamingContext context)
            : base(info, context)
        {

        }
    }
}