C#: معدِّلات الوصول والخصائص

public class Animal
{
    public string Species;
    private int health = 100;
    protected int energy = 90;
    internal string category = "Mammal";

    public void ShowInfo()
    {
        Console.WriteLine($"Species: {Species}, Health: {health}, Energy: {energy}, Category: {category}");
    }

    public void SetHealth(int h) { health = h; }
}

public class Dog : Animal
{
    public void Run()
    {
        energy -= 10;
        category = "Mammal";
    }
}

class Program
{
    static void Main()
    {
        Animal a = new Dog { Species = "Dog" };
        a.ShowInfo();
        ((Dog)a).Run();
        a.ShowInfo();
    }
}

Species: Dog, Health: 100, Energy: 90, Category: Mammal
Species: Dog, Health: 100, Energy: 80, Category: Mammal

public class BankAccount
{
    private decimal balance;

    public decimal Balance
    {
        get { return balance; }
        set
        {
            if (value < 0)
                throw new ArgumentException("Balance cannot be negative");
            balance = value;
        }
    }
}

var account = new BankAccount();
account.Balance = 1000m;
Console.WriteLine($"Balance: {account.Balance}");

Balance: 1000

public class Student
{
    private string name;

    public string Name
    {
        get { return name; }
        set
        {
            if (string.IsNullOrWhiteSpace(value))
                throw new ArgumentException("Name cannot be empty");
            name = value;
        }
    }
}

var s = new Student();
s.Name = "Alice";
Console.WriteLine(s.Name);

Alice

public class Product
{
    public string Name { get; set; }
    public decimal Price { get; set; }
}

var p = new Product { Name = "Pen", Price = 2.5m };
Console.WriteLine($"{p.Name}: ${p.Price}");

Pen: $2.5

public class Config
{
    public string Host { get; }
    public int Port { get; }
    public Config(string host, int port)
    {
        Host = host;
        Port = port;
    }
}

class Program
{
    static void Main()
    {
        var cfg = new Config("localhost", 8080);
        System.Console.WriteLine($"{cfg.Host}:{cfg.Port}");
    }
}

localhost:8080

public class Circle
{
    public double Radius { get; }

    public Circle(double radius)
    {
        Radius = radius;
    }
}

var c = new Circle(5.0);
Console.WriteLine($"Radius: {c.Radius}");

Radius: 5

public class Rectangle
{
    public double Width { get; set; }
    public double Height { get; set; }

    public double Area => Width * Height;
    public double Perimeter => 2 * (Width + Height);
}

var r = new Rectangle { Width = 3, Height = 4 };
Console.WriteLine($"Area: {r.Area}, Perimeter: {r.Perimeter}");

Area: 12, Perimeter: 14

public class User
{
    public string Name { get; }
    public string Email { get; }
    public int Age { get; }
    public User(string name, string email, int age)
    {
        Name = name;
        Email = email;
        Age = age;
    }
}

class Program
{
    static void Main()
    {
        var u = new User("Bob", "bob@test.com", 25);
        System.Console.WriteLine($"{u.Name} ({u.Email})");
    }
}

Bob (bob@test.com)

public class Person : IEquatable<Person>
{
    public string Name { get; }
    public int Age { get; }
    public Person(string name, int age)
    {
        Name = name;
        Age = age;
    }
    public bool Equals(Person other)
    {
        return other != null && Name == other.Name && Age == other.Age;
    }
    public override bool Equals(object obj) => Equals(obj as Person);
    public override int GetHashCode() => System.HashCode.Combine(Name, Age);
    public override string ToString() => $"Person {{ Name = {Name}, Age = {Age} }}";
}

class Program
{
    static void Main()
    {
        var p1 = new Person("Alice", 30);
        var p2 = new Person("Alice", 30);
        System.Console.WriteLine($"Equal: {p1 == p2}");
        System.Console.WriteLine(p1);
    }
}

var p1 = new Person("Alice", 30);
var p2 = new Person("Alice", 30);
Console.WriteLine($"Equal: {p1 == p2}");
Console.WriteLine(p1);

Equal: True
Person { Name = Alice, Age = 30 }