Hi Guys,

I host my asp.net core website on Asphostportal. I'm trying to see if I can merge my old projects Program.cs and Startup.cs files into just the Program.cs file. I upgraded the application to .NET 6, and having them separate works, but I'm trying to really learn what the difference is like.

-- Startup.cs

HTML Code:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Identity;
using Microsoft.AspNetCore.Identity.UI;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.HttpsPolicy;
using Microsoft.EntityFrameworkCore;
using IssueTracker2020.Data;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using IssueTracker2020.Models;
using IssueTracker2020.Services;
using IssueTracker2020.Utilities;
using Microsoft.AspNetCore.Identity.UI.Services;

namespace IssueTracker2020
{
    public class Startup
    {
        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;
        }

        public IConfiguration Configuration { get; }

        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            //services.AddMvc().AddRazorPagesOptions(options =>
            //{
            //    options.Conventions.AddPageRoute("/Pages/Account/Login", "");
            //});

            services.AddDbContext<ApplicationDbContext>(options =>
                options.UseNpgsql(
                    DataHelper.GetConnectionString(Configuration)));

            services.AddIdentity<BTUser, IdentityRole>(options => options.SignIn.RequireConfirmedAccount = false)
                .AddEntityFrameworkStores<ApplicationDbContext>()
                .AddDefaultUI()
                .AddDefaultTokenProviders();

            services.AddScoped<IBTRolesService, BTRolesService>();
            services.AddScoped<IBTProjectService, BTProjectService>();
            services.AddScoped<IBTHistoryService, BTHistoryService>();
            services.AddScoped<IBTAccessService, BTAccessService>();
            services.AddScoped<INotificationService, NotificatonService>();
            services.AddScoped<IBTFileService, BTFileService>();
            services.AddScoped<ITicketService, TicketService>();

            // Email Register
            services.Configure<MailSettings>(Configuration.GetSection("MailSettings"));
            services.AddTransient<IEmailSender, EmailService>();

            services.AddControllersWithViews();
            services.AddRazorPages();
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
                app.UseDatabaseErrorPage();
            }
            else
            {
                app.UseExceptionHandler("/Home/Error");
                // The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
                app.UseHsts();
            }
            app.UseHttpsRedirection();
            app.UseStaticFiles();

            app.UseRouting();

            app.UseAuthentication();
            app.UseAuthorization();

            app.UseEndpoints(endpoints =>
            {
                endpoints.MapControllerRoute(
                    name: "default",
                    pattern: "{controller=Home}/{action=LandingPage}/{id?}");
                endpoints.MapRazorPages();
            });
        }
    }
}
-- Program.cs

HTML Code:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using IssueTracker2020.Data;
using IssueTracker2020.Models;
using IssueTracker2020.Utilities;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Identity;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;

namespace IssueTracker2020
{
    public class Program
    {
        public async static Task Main(string[] args)
        {
            //CreateHostBuilder(args).Build().Run();
            var host = CreateHostBuilder(args).Build();
            await DataHelper.ManageData(host);
            using (var scope = host.Services.CreateScope())
            {
                var services = scope.ServiceProvider;
                var loggerFactory = services.GetRequiredService<ILoggerFactory>();
                try
                {
                    var context = services.GetRequiredService<ApplicationDbContext>();
                    var userManager = services.GetRequiredService<UserManager<BTUser>>();
                    var roleManager = services.GetRequiredService<RoleManager<IdentityRole>>();
                    await ContextSeed.RunSeedMethodsAsync(roleManager, userManager, context);
                }
                catch (Exception ex)
                {
                    var logger = loggerFactory.CreateLogger<Program>();
                    logger.LogError(ex, "An error occurred seeding the DB.");
                }
            }
            host.Run();
        }

        public static IHostBuilder CreateHostBuilder(string[] args) =>
            Host.CreateDefaultBuilder(args)
                .ConfigureWebHostDefaults(webBuilder =>
                {
                    webBuilder.CaptureStartupErrors(true);
                    webBuilder.UseSetting(WebHostDefaults.DetailedErrorsKey, "true");
                    webBuilder.UseStartup<Startup>();
                });
    }
}
Thank you