using System;

using System.Linq;

using System.Threading.Tasks;

using Microsoft.Extensions.Logging;

using Microsoft.Extensions.DependencyInjection;

public class Program

{

    public static void Main(string[] args)

    {

        var serviceProvider = new ServiceCollection()

            .AddLogging(lb => {

                lb.ClearProviders();

                lb.AddConsole();

            })

            .BuildServiceProvider();

        Console.WriteLine("12345".TakeLast(4).GetType().FullName);

        using (var scope = serviceProvider.CreateScope())

        {

            var secretNumber = "123456789";

            var logger = scope.ServiceProvider.GetService<ILogger<Program>>();

            logger.LogInformation("Take 1: {valueProp}", secretNumber?.TakeLast(4));

            logger.LogInformation("Take 2: {valueProp}", secretNumber?.TakeLast(4).ToString());

            logger.LogInformation("Take 3: {valueProp}", secretNumber?.Substring(secretNumber.Length - 4));

            logger.LogInformation("Take 4: {valueProp}", secretNumber?[^4..]);

            logger.LogInformation("Take 5: {valueProp}", new String(secretNumber?.TakeLast(4).ToArray())); // Safest if secret number is less than 4 digits long

        }

        Task.Delay(100).Wait(); // Let the logger write

    }

}