Vorislik va interfeyslar

var t = new Talaba("Husanboy", 25, "Informatika");
var o = new Oqituvchi("Nodira", 40, "Matematika");

t.Tanishtir();
o.Tanishtir();

class Shaxs(string ism, int yosh)
{
    public string Ism => ism;
    public int Yosh => yosh;

    public virtual void Tanishtir()
    {
        Console.WriteLine($"Men {Ism}, {Yosh} yoshdaman");
    }
}

class Talaba(string ism, int yosh, string yonalish) : Shaxs(ism, yosh)
{
    public string Yonalish => yonalish;

    public override void Tanishtir()
    {
        base.Tanishtir();
        Console.WriteLine($"  {Yonalish} yo'nalishi talabasiman");
    }
}

class Oqituvchi(string ism, int yosh, string fan) : Shaxs(ism, yosh)
{
    public override void Tanishtir()
    {
        Console.WriteLine($"Men {Ism}, {fan} o'qituvchisiman");
    }
}

Shakl[] shakllar =
[
    new Doira(5),
    new Togritortburchak(4, 6)
];

foreach (Shakl shakl in shakllar)
{
    Console.WriteLine($"{shakl.Nomi,-16} maydoni = {shakl.Maydon():F2}");
}

abstract class Shakl
{
    public abstract string Nomi { get; }
    public abstract double Maydon();
}

class Doira(double radius) : Shakl
{
    public override string Nomi => "Doira";
    public override double Maydon() => Math.PI * radius * radius;
}

class Togritortburchak(double eni, double boyi) : Shakl
{
    public override string Nomi => "To'rtburchak";
    public override double Maydon() => eni * boyi;
}

IYozuvchi[] chiqishlar = [new Konsolga(), new Xotiraga()];

foreach (IYozuvchi yozuvchi in chiqishlar)
{
    yozuvchi.Yoz("Salom");
    yozuvchi.Yoz("Dunyo");
}

(chiqishlar[1] as Xotiraga)?.Korsat();

interface IYozuvchi
{
    void Yoz(string matn);
}

class Konsolga : IYozuvchi
{
    public void Yoz(string matn) => Console.WriteLine($"[konsol] {matn}");
}

class Xotiraga : IYozuvchi
{
    private readonly List<string> qatorlar = [];

    public void Yoz(string matn) => qatorlar.Add(matn);

    public void Korsat() => Console.WriteLine(
        $"[xotira] {qatorlar.Count} qator: {string.Join(", ", qatorlar)}");
}

var h = new Hujjat("Hisobot");
h.Saqla();
h.Chop();

interface ISaqlanadigan
{
    void Saqla();
}

interface IChopEtiladigan
{
    void Chop();
}

class Hujjat(string nom) : ISaqlanadigan, IChopEtiladigan
{
    public void Saqla() => Console.WriteLine($"{nom} saqlandi");
    public void Chop() => Console.WriteLine($"{nom} chop etildi");
}

object[] narsalar = [new Doira(2), new Kvadrat(3), "matn"];

foreach (object narsa in narsalar)
{
    if (narsa is Shakl shakl)
    {
        Console.WriteLine($"Shakl, maydoni {shakl.Maydon():F2}");
    }
    else
    {
        Console.WriteLine($"Shakl emas: {narsa.GetType().Name}");
    }
}

abstract class Shakl
{
    public abstract double Maydon();
}

class Doira(double r) : Shakl
{
    public override double Maydon() => Math.PI * r * r;
}

class Kvadrat(double t) : Shakl
{
    public override double Maydon() => t * t;
}

var x = new Yakuniy();
Console.WriteLine(x.Salom());

sealed class Yakuniy
{
    public string Salom() => "Mendan meros olib bo'lmaydi";
}