using System;

using System.Linq;

using System.Collections.Generic;

using System.Collections;

​

public class Program

{

    public static void Main()

    {

        int[] awesomeNumbers = {4,2,49,21,92,39,10,08,73,94,81,95,14};

        string[] emptyBasket = {};

        string[] fruits = {"apple", "mango", "yakfruit", "canneryfruit", "orange", "passionfruit", "grape", "pear"};

        string[] fruits2 = {"apple", "yakfruit", "orange", "grape", "pear", "watermelon"};

        string[] largeFruits = {"watermelon", "papaya", "dragonfruit", "jackfruit"};

        string[] grape = {"grape"};

        int[] emptyArray = {};

        // Create list of different types

        List<object> mixedList = new List<object>();

        mixedList.Add(12);

        mixedList.Add("Keyara");

        mixedList.Add(new Product("8th Portal", 8859));

        mixedList.Add(84);

        mixedList.Add(emptyArray);

        mixedList.Add("Samantha");

        mixedList.Add("Doug");

        mixedList.Add(awesomeNumbers);

        mixedList.Add(new Product("5th Portal", 4929));

        mixedList.Add(new Product("11th Portal", 3364));

        // Find and list the strings in mixedList

        IEnumerable<string> stringsInMixedList = mixedList.OfType<string>();

        Console.WriteLine("Strings in mixedList:");

        foreach (string S in stringsInMixedList){

            Console.WriteLine(S);   

        }

        Console.WriteLine();

        // Find and list the Portals with a number below 5000

        IEnumerable<Product> productsBelow5000 = mixedList.OfType<Product>().Where(thisProduct => thisProduct.Code < 5000);

        Console.WriteLine("Products with a code less than 5000:");

        foreach (Product P in productsBelow5000){

            Console.WriteLine("Product Name: {0} - Product Code: {1}", P.Name, P.Code); 

        }

        Console.WriteLine();

        // List the items in mixedList and their type

        foreach (object O in mixedList){

            if (O.GetType().ToString() == "Product"){

                Product oProd = (Product)O;

                Console.WriteLine("object: {0} - object type: {1}", oProd.Name, O.GetType());

            }

            // Display the entire set of numbers if it is an array of ints

            else if (O.GetType().ToString() == "System.Int32[]"){

                int[] oInt = (int[])O;

                foreach (int i in oInt){

                    Console.Write(i + " ");

                }

                Console.Write("\n");

            }

            else{

                Console.WriteLine("object: {0} - object type: {1}", O, O.GetType());

            }

        }

        Console.WriteLine();

        Console.WriteLine("---");

        // Example from Microsoft Docs https://docs.microsoft.com/en-us/dotnet/api/system.linq.enumerable.oftype?view=netframework-4.8

        ArrayList fruitsFromMicrosoft = new ArrayList(4);

        fruitsFromMicrosoft.Add("Mango");

        fruitsFromMicrosoft.Add("Orange");

        fruitsFromMicrosoft.Add("Apple");

        fruitsFromMicrosoft.Add(3.0);

        fruitsFromMicrosoft.Add("Banana");

​

        // Apply OfType() to the ArrayList.

        IEnumerable<string> query1 = fruitsFromMicrosoft.OfType<string>();

​

        Console.WriteLine("Elements of type 'string' are:");

        foreach (string fruit in query1)

        {

            Console.WriteLine(fruit);

        }

​

        // The following query shows that the standard query operators such as 

        // Where() can be applied to the ArrayList type after calling OfType().

        IEnumerable<string> query2 =

            fruitsFromMicrosoft.OfType<string>().Where(fruit => fruit.ToLower().Contains("n"));

​

        Console.WriteLine("\nThe following strings contain 'n':");

        foreach (string fruit in query2)

        {

            Console.WriteLine(fruit);

        }

    }

}

public class Pet

{

    // Attributes

    public string Name{ get; set;}

    public int Age{ get; set;}

}

​

public class Building

{

    // Attributes

    public string Name{ get; set;}

    public string Address{ get; set;}

    public int Number{ get; set;}

    // Constructors

    public Building(){}

    public Building(string name, string addy, int num){

        this.Name = name;

        this.Address = addy;

        this.Number = num;

    }

}

​

public class Tenant

{

    // Attributes

    public string Name{ get; set;}

    public int BuildingNumber{ get; set;}

    // Constructors

    public Tenant(){}

    public Tenant(string name, int BN){

        this.Name = name;

        this.BuildingNumber = BN;

    }

}

​

public class Product

{

    // Attributes

    public string Name { get; set; }

    public int Code { get; set; }

    // Constructors

    public Product(){}

    public Product(string n, int c){

        this.Name = n;

        this.Code = c;

    }

}

​

// Custom comparer for the Product class

class ProductComparer : IEqualityComparer<Product>

{

    // Products are equal if their names and product numbers are equal.

    public bool Equals(Product x, Product y)

    {

        //Check whether the compared objects reference the same data.

        if (Object.ReferenceEquals(x, y)) return true;

​

        //Check whether any of the compared objects is null.

        if (Object.ReferenceEquals(x, null) || Object.ReferenceEquals(y, null))

            return false;

​

        //Check whether the products' properties are equal.

        return x.Code == y.Code && x.Name == y.Name;

    }

​

    // If Equals() returns true for a pair of objects 

    // then GetHashCode() must return the same value for these objects.

​

    public int GetHashCode(Product product)

    {

        //Check whether the object is null

        if (Object.ReferenceEquals(product, null)) return 0;

​

        //Get hash code for the Name field if it is not null.

        int hashProductName = product.Name == null ? 0 : product.Name.GetHashCode();

​

        //Get hash code for the Code field.

        int hashProductCode = product.Code.GetHashCode();

​

        //Calculate the hash code for the product.

        return hashProductName ^ hashProductCode;

    }

}