Program.cs

using System;
using System.Collections.Generic;

namespace ConsoleApp1
{
    class Program
    {
        static void Main(string[] args)
        {
            //var integerList = new List<int>();
            ////var integerList = new List<int> {1, 2, 3, 4} ;
            //integerList.Add(1);
            //integerList.Add(2);
            //integerList.Add(3);
            //integerList.Add(4);
            //integerList.Remove(2);
            //foreach (var integer in integerList)
            //{
            //    Console.WriteLine(integer);
            //}
            var user1 = new User();
            user1.Username = "gigi";
            user1.Password = "gigieparola";
            user1.Email = "gigi@gmail.com";
            user1.Age = 20;

            var user2 = new User("Andrei", "parolamea", "email@gmail.com", 12);
            var user3 = new User("AndreiAndrei", "parolameanueasta", "email@gmail.com", 122);

            var userList = new List<User>();
            userList.Add(user1);
            userList.Add(user2);
            userList.Add(user3);

            //foreach (var user in userList)
            //{
            //    Console.WriteLine($"Username = {user.Username} & Age = {user.Age} ");
            //}
            var userService = new UserService(userList);
            //var usersOver18 = userService.GetUsersOver18Linq();

            //usersOver18.ForEach(user => Console.WriteLine(user.Username));

            //var userHavingPasswordStartingWithSpecificString = userService.GetUserWithPasswordStartingWithSomething("parola");
            //Console.WriteLine(userHavingPasswordStartingWithSpecificString.Username);


            Console.WriteLine(userService.LoginTrue("Andrei","parolamea"));
            Console.WriteLine(userService.Exist("Andrei"));
            //daca are gmail la email
        }
    }
}