#nullable enable

​

using System;

using System.Collections.Generic;

using System.Linq;

​

public class Program

{

    public static void Main()

    {

        var userNames = new List<string>{"Pelle Coltau", "Søren Lund"};

        var persons = userNames.Select(x => new Person{Name = x});

        foreach (var person in persons)

        {

            person.FamilyName = person.Name.Split(' ').Last();

        }

​

        var familyNameList = persons.Select(x => x.FamilyName).ToList();

        Console.WriteLine(string.Join(", ", familyNameList));

    }

​

    private class Person

    {

        public required string Name { get; init; }

​

        public string? FamilyName { get; set; }

    }

}

​

#nullable disable