public class User
{
    public int Id { get; set; }
    public string Name { get; set; }
}

public class AppDbContext : DbContext
{
    public DbSet<User> Users { get; set; }

    protected override void OnConfiguring(DbContextOptionsBuilder options)
        => options.UseSqlServer("Server=.;Database=TestDb;Trusted_Connection=True;");
}

dotnet ef migrations add InitialCreate
dotnet ef database update

dotnet ef dbcontext scaffold "Server=.;Database=TestDb;Trusted_Connection=True;" Microsoft.EntityFrameworkCore.SqlServer -o Models

using System;
using System.Collections;

public class DaysOfWeek : IEnumerable
{
    private string[] days = { "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday", "Sunday" };

    public IEnumerator GetEnumerator()
    {
        for (int index = 0; index < days.Length; index++)
        {
            // Yield each day of the week.
            yield return days[index];
        }
    }
}

public class Program
{
    public static void Main()
    {
        DaysOfWeek daysOfWeek = new DaysOfWeek();
        foreach (string day in daysOfWeek)
        {
            Console.WriteLine(day);
        }
    }
}

public interface IMediator
{
    void Notify(object sender, string ev);
}   

public class DialogMediator : IMediator
{
    private Button _button;
    private TextBox _textBox;

    public DialogMediator(Button button, TextBox textBox)
    {
        _button = button;
        _button.SetMediator(this);
        _textBox = textBox;
        _textBox.SetMediator(this);
    }

    public void Notify(object sender, string ev)
    {
        if (ev == "ButtonClick")
        {
            _textBox.Clear();
        }
        else if (ev == "TextBoxEnter")
        {
            _button.SetEnabled(true);
        }
    }
}   

public class Button
{
    private IMediator _mediator;
       
    public void SetMediator(IMediator mediator)
    {
        _mediator = mediator;
    }

    public void Click()
    {
        Console.WriteLine("Button clicked");
        _mediator.Notify(this, "ButtonClick");
    }

    public void SetEnabled(bool enabled)
    {
        Console.WriteLine($"Button is {(enabled ? "enabled" : "disabled")}");
    }
}

public class TextBox
{
    private IMediator _mediator;
       
    public void SetMediator(IMediator mediator)
    {
        _mediator = mediator;
    }

    public void EnterText()
    {
        Console.WriteLine("Text entered");
        _mediator.Notify(this, "TextBoxEnter");
    }

    public void Clear()
    {
        Console.WriteLine("TextBox cleared");
    }
}  

var button = new Button();
var textBox = new TextBox();
var mediator = new DialogMediator(button, textBox);

textBox.EnterText(); // Ввод текста активирует кнопку
button.Click();      // Нажатие кнопки очищает текстовое поле   

public class Utils
{
    public static void Print<T>(T value) // Обобщённый метод
    {
        Console.WriteLine($"Тип: {typeof(T)}, Значение: {value}");
    }
}

class Program
{
    static void Main()
    {
        Utils.Print(100);      // Тип: System.Int32, Значение: 100
        Utils.Print("Hello");  // Тип: System.String, Значение: Hello
        Utils.Print(3.14);     // Тип: System.Double, Значение: 3.14
    }
}

public class GenericList<T>
{
    private T[] elements;
    private int size;

    public GenericList(int size)
    {
        elements = new T[size];
        this.size = size;
    }

    public void Add(T element)
    {
        // Логика добавления элемента
    }

    public T this[int i]
    {
        get { return elements[i]; }
        set { elements[i] = value; }
    }
}

public T GenericMax<T>(T x, T y) where T : IComparable
{
    return x.CompareTo(y) > 0 ? x : y;
}

public class Person
{
    public string Name { get; set; }
    public int Age { get; set; }
}

using System.ComponentModel;
using System.Runtime.CompilerServices;

public class PersonViewModel : INotifyPropertyChanged
{
    private string _name;
    public string Name
    {
        get => _name;
        set { _name = value; OnPropertyChanged(); }
    }

    public event PropertyChangedEventHandler PropertyChanged;
    protected void OnPropertyChanged([CallerMemberName] string propertyName = null)
        => PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}

<TextBox Text="{Binding Name, Mode=TwoWay}" />
<TextBlock Text="{Binding Name}" />

using (var file = new StreamWriter("file.txt"))
{
    file.WriteLine("Привет, мир!");
}

StreamWriter file = new StreamWriter("file.txt");
try
{
    file.WriteLine("Привет, мир!");
}
finally
{
    if (file != null)
        file.Dispose(); // Автоматический вызов Dispose()
}

await using (var file = new AsyncResource())
{
    await file.DoSomethingAsync();
}

var file = new AsyncResource();
try
{
    await file.DoSomethingAsync();
}
finally
{
    if (file != null)
        await file.DisposeAsync();
}