класс-коллекцию логинов и паролей/пример с магазином

gistfile1.txt

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication13
{

    public class NoRecordsInCollection : Exception
    {
        public NoRecordsInCollection() : base() { }
    }

    public class LoginAlreadyAdded : Exception
    {
        public LoginAlreadyAdded() : base() { }
    }

    public class LoginNotFound : Exception
    {
        public LoginNotFound() : base() { }
    }

    public class CEncryption
    {
        public static string Encrypt(string strIn, string strKey)
        {
            string sbOut = String.Empty;
            for (int i = 0; i < strIn.Length; i++)
            {
                sbOut += String.Format("{0:00}", strIn[i] ^ strKey[i % strKey.Length]);
            }

            return sbOut;
        }

        public static string Decrypt(string strIn, string strKey)
        {
            string sbOut = String.Empty;
            for (int i = 0; i < strIn.Length; i += 2)
            {
                byte code = Convert.ToByte(strIn.Substring(i, 2));
                sbOut += (char)(code ^ strKey[(i / 2) % strKey.Length]);
            }

            return sbOut;
        }
    }

    public class LoginPasswordCollection
    {
        struct Record
        {
            public String login;

            public String password;
        }

        private Record[] recordContainer;

        public int Count
        {
            get
            {
                if (recordContainer == null)
                {
                    return 0;
                }
                else
                {
                    return recordContainer.Length;
                }
            }
        }

        public void ShowLogins()
        {
            for (int i = 0; i < recordContainer.Length; i++)
            {
                Console.WriteLine(recordContainer[i]);
            }
        }

        public String this[int ind]
        {
            get
            {
                if (ind >= recordContainer.Length)
                    throw new NoRecordsInCollection();
                return recordContainer[ind].login;
            }
        }

        public String this[String login]
        {
            get
            {
                if (recordContainer.Length == 0)
                    throw new NoRecordsInCollection();

                for (int i = 0; i < recordContainer.Length; i++)
                {
                    if (recordContainer[i].login.Equals(login))
                    {
                        return DecryptPassword(recordContainer[i].password);
                    }
                }

                return "";
            }
        }

        public Boolean IsLoginAdded(String login)
        {
            if (recordContainer == null)
                return false;

            for (int i = 0; i < recordContainer.Length; i++)
            {
                if (recordContainer[i].Equals(login))
                    return true;
            }

            return false;
        }

        public void AddUser(String login, String password)
        {
            if(recordContainer == null)
            {
                recordContainer = new Record[1];
                recordContainer[0].login = login;
                recordContainer[0].password = EncryptPassword(password);
            }
            else
            {
                if (IsLoginAdded(login))
                    throw new LoginAlreadyAdded();

                Record[] buffer = new Record[recordContainer.Length + 1];

                for (int i = 0; i < recordContainer.Length; i++)
                {
                    buffer[i] = recordContainer[i];
                }

                buffer[recordContainer.Length].login = login;
                buffer[recordContainer.Length].password = EncryptPassword(password);

                recordContainer = buffer;
            }            
                      
        }

        public void DeleteUserData(String login)
        {

        }

        private String EncryptPassword(String originalPassword)
        {
            return CEncryption.Encrypt(originalPassword, "dotnet");
        }

        private String DecryptPassword(String cryptedPassword)
        {
            return CEncryption.Decrypt(cryptedPassword, "dotnet");
        }
    }
}

////////////////////////////////////////////////////////

namespace ConsoleApplication14
{

    public abstract class Device
    {

        public Device(String category)
        {
            Category = category;
        }

        public Double Price
        {
            get;
            set;
        }

        public String Vendor
        {
            get;
            set;
        }

        public String Category
        {
            get;
        }

        public DateTime ProduceYear
        {
            get;
            set;
        }

        public Boolean Warranty
        {
            get;
            set;
        }

        public String Model
        {
            get;
            set;
        }
                     
    }

    public class Laptop : Device
    {
        public Laptop() : base("Laptop") {  }
    }

    public class Recharge : Device
    {
        public Recharge() : base("Recharge") { }
    }

    public class Tablet : Device
    {
        public Tablet() : base("Tablet") { }
    }

    public class MobilePhone : Device
    {
        public MobilePhone() : base("MobilePhone")
        {
        }
    }

    public class Cover : Device
    {
        public Cover() : base("Cover") { }
    }

    public class NoMorePlaceInStore : Exception
    {
        public NoMorePlaceInStore() : base() { }
    }

    public class Store
    {
        private Device[] devicesInStore;

        private int count;

        public Store(uint size)
        {
            devicesInStore = new Device[size];
        }

        public int Size
        {
            get { return devicesInStore.Length; }
        }

        public int Count
        {
            get { return count; }
        }

        public void addDevice(Device newDevice)
        {
            if (Count == Size)
            {
                throw new NoMorePlaceInStore();
            }

            devicesInStore[Count] = newDevice;
            count++;
        }

        public void findByPrice(int minPrice, int maxPrice)
        {
            for (int i = 0; i < Count; i++)
            {
                if (devicesInStore[i].Price >= minPrice && devicesInStore[i].Price <= maxPrice)
                {
                    showDevice(devicesInStore[i]);
                }
            }       
        }

        public Device this[String model]
        {
            get
            {
                for (int i = 0; i < Count; i++)
                {
                    if (devicesInStore[i].Model.Equals(model))
                    {
                        return devicesInStore[i];
                    }
                }

                return null;
            }
        }

        public Device this[DateTime produceYear]
        {
            get
            {
                for (int i = 0; i < Count; i++)
                {
                    if (devicesInStore[i].ProduceYear == produceYear)
                    {
                        return devicesInStore[i];
                    }
                }

                return null;
            }
        }

        public void findByCategory(String category)
        {
            for (int i = 0; i < Count; i++)
            {
                if (devicesInStore[i].Category == category)
                {
                    showDevice(devicesInStore[i]);
                }
            }
        }

        private void showDevice(Device dev)
        {
            Console.WriteLine(dev.Model + " | " + dev.Price);
        }

    }
}