linq by Jean, C# - rextester

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//Rextester.Program.Main is the entry point for your code. Don't change it.
//Compiler version 4.0.30319.17929 for Microsoft (R) .NET Framework 4.5

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;

namespace Rextester
{
    class Program
    {
        public static void Main(string[] args)
        {
            var persons = new List<Person>();
            Random rnd = new Random();
            #region Arr
            persons.AddRange(new Person[]{
                new Person
                {
                    Name = "Fausto",
                    LastName = "Garces",
                    Age = 32,
                    City = "Santo Domingo",
                    Country = "The World"
                },
                new Person
                {
                    Name = "Jean",
                    LastName = "Peña",
                    Age = 26,
                    City = "Santo Domingo",
                    Country = "Dominican Republic"
                },
                new Person
                {
                    Name = "Ramon",
                    LastName = "Rodriguez",
                    Age = 2364,
                    City = "Santo Domingo",
                    Country = "Dominican Republic"
                },
                new Person
                {
                    Name = "Manuel",
                    LastName = "Gonzalez",
                    Age = 28,
                    City = "Azua",
                    Country = "Dominican Republic"
                },
                new Person
                {
                    Name = "Fernando",
                    LastName = "Espinosa",
                    Age = 32,
                    City = "Bani",
                    Country = "Dominican Republic"
                },
                new Person
                {
                    Name = "Eugenio",
                    LastName = "Duran",
                    Age = 12,
                    City = "Miami FL",
                    Country = "United State"
                },
            });
            #endregion

var youndPeople = persons.Where(p => p.Age > 18).ToList();

var students = persons.Select(p => new Student
            {
                person = p,
                course = rnd.Next(100)
            }).ToList();

persons.ForEach((p) =>
            {
                Console.WriteLine("Nombre: {0}; Edad:{1}; Pais:{2}", p.Name, p.Age, p.Country);
            });

Console.WriteLine("");
            Console.WriteLine("");

students.ForEach((p) =>
            {
                Console.WriteLine("Nombre: {0}; Edad:{1}; Pais:{2}; Curso:{3}", p.person.Name, p.person.Age, p.person.Country, p.course);
            });

Console.WriteLine("");
            Console.WriteLine("");

persons.GroupBy(p => p.Country)
                .Select(gp => new {
                    Country = gp.Select(g => g.Country).FirstOrDefault(),
                    Count = gp.Count()
                }).ToList().ForEach(
                (gg) =>
                {
                    Console.WriteLine("Country: {0}; Count:{1}", gg.Country, gg.Count);
                });

//Console.ReadKey();
        }
    }

class Person
    {
        public String Name { get; set; }
        public String LastName { get; set; }
        public int Age { get; set; }
        public String City { get; set; }
        public String Country { get; set; }
    }

class Student
    {
        public Person person { get; set; }
        public int course { get; set; }
    }
}

Show compiler warnings [ + ] Show input
Compilation time: 0,22 sec, absolute running time: 0,14 sec, cpu time: 0,12 sec, average memory usage: 14 Mb, average nr of threads: 3