using System;

using System.Collections.Generic;

using System.Linq;

    public class Program

    {

        public static void Main(string[] args)

        {

            var adults = new List<Adult>

            {

                new Adult

                {

                    FirstName = "Robert",

                    Job = "Junior Developer"

                },

                new Adult {

                    FirstName = "Micah",

                    Job = "Developer"

                }

            };

​

            var children = new List<Child>

            {

                new Child

                {

                    FirstName = "Zoie",

                    SchoolName = "Piper Ranch"

                },

                new Child

                {

                    FirstName = "Brandon",

                    SchoolName = "Piper Ranch"

                }

            };

​

            var people = new List<IFirstName>(adults);

            people.AddRange(children);

​

            foreach (var person in people)

            {

                Console.WriteLine(person.FirstName);

            }

            Console.WriteLine("Print all names using an interface\n\n");

​

            foreach (var person in people)

            {

                if (person is Child)

                {

                    var child = (Child)person;

​

                    Console.WriteLine(child.SchoolName);

                } else if (person is Adult)

                {

                    var adult = (Adult)person;

                    Console.WriteLine(adult.Job);

                }

            }

            Console.WriteLine("Print Schools and Job names by using the classes to know the difference\n\n");

​

            //A little complicated

            PrintFirstNames(adults);

            PrintFirstNames(children);

            Console.WriteLine("Print first names using a generic method\n\n");

​

            var firstNamesUsingConcat = adults.Select(t => t.FirstName).Concat(children.Select(t => t.FirstName)).ToList();

            foreach (var firstName in firstNamesUsingConcat)

            {

                Console.WriteLine(firstName);

            }

​

            Console.WriteLine("Print first names by concatenating the adults and children lists and selecting only the first names\n\n");

​

            var adultsAndChildrenList = adults.Select(t => t as Person).Concat(children.Select(t => t as Person)).ToList();

            foreach (var person in adultsAndChildrenList)

            {

                Console.WriteLine(person.FirstName);

            }

​

            Console.WriteLine("Print first names by creating one list of Person by selecting each item from adults and children as a Person\n\n");

​

            Console.ReadLine();

        }

​

        private static void PrintFirstNames<T>(List<T> people) where T : Person

        {

            foreach (var person in people)

            {

                Console.WriteLine(person.FirstName);

            }

        }

    }

​

    public class Person

    {

        public string FirstName { get; set;}

        public string LastName { get; set; }

        public string Age { get; set; }

    }

​

    public class Child : Person, IFirstName

    {

        public string SchoolName { get; set; }

    }

​

    public class Adult : Person, IFirstName

    {

        public string Job { get; set; }

    }

​

    public interface IFirstName

    {

        string FirstName { get; set; }

    }