C#: الفئات المجردة والواجهات

abstract class Shape
{
    public string Name { get; set; }

    public abstract double Area();

    public void Print()
    {
        Console.WriteLine($"{Name} Area: {Area():F2}");
    }
}

class Circle : Shape
{
    public double Radius { get; set; }

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

    public override double Area()
    {
        return Math.PI * Radius * Radius;
    }
}

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

    public Rectangle(double w, double h)
    {
        Name = "Rectangle";
        Width = w;
        Height = h;
    }

    public override double Area()
    {
        return Width * Height;
    }
}

Circle c = new Circle(3);
Rectangle r = new Rectangle(4, 5);
c.Print();
r.Print();

Circle Area: 28.27
Rectangle Area: 20.00

abstract class Logger
{
    protected string prefix;

    public Logger(string prefix)
    {
        this.prefix = prefix;
    }

    public abstract void Log(string message);

    public void LogWithTimestamp(string message)
    {
        string ts = DateTime.Now.ToString("HH:mm:ss");
        Log($"[{ts}] {message}");
    }
}

class FileLogger : Logger
{
    public FileLogger() : base("FILE") { }

    public override void Log(string message)
    {
        Console.WriteLine($"{prefix}: {message}");
    }
}

FileLogger fl = new FileLogger();
fl.Log("Service started");
fl.LogWithTimestamp("Database connected");

FILE: Service started
FILE: [14:30:00] Database connected

interface IMovable
{
    void Move(double dx, double dy);
    double Speed { get; set; }
}

interface IDrawable
{
    void Draw();
}

class Player : IMovable, IDrawable
{
    public double X { get; set; }
    public double Y { get; set; }
    public double Speed { get; set; }

    public Player(double x, double y, double speed)
    {
        X = x;
        Y = y;
        Speed = speed;
    }

    public void Move(double dx, double dy)
    {
        X += dx * Speed;
        Y += dy * Speed;
        Console.WriteLine($"Moved to ({X:F1}, {Y:F1})");
    }

    public void Draw()
    {
        Console.WriteLine($"Drawing player @ ({X:F1}, {Y:F1})");
    }
}

Player p = new Player(0, 0, 2.0);
p.Draw();
p.Move(3, 4);
p.Draw();

Drawing player @ (0.0, 0.0)
Moved to (6.0, 8.0)
Drawing player @ (6.0, 8.0)

interface IWalkable
{
    void Walk();
}

interface ISwimmable
{
    void Swim();
}

interface IFlyable
{
    void Fly();
}

class Duck : IWalkable, ISwimmable, IFlyable
{
    public string Name { get; set; }

    public Duck(string name)
    {
        Name = name;
    }

    public void Walk()
    {
        Console.WriteLine($"{Name} waddles along");
    }

    public void Swim()
    {
        Console.WriteLine($"{Name} swims in the water");
    }

    public void Fly()
    {
        Console.WriteLine($"{Name} flaps its wings and takes off");
    }
}

Duck d = new Duck("Donald");
d.Walk();
d.Swim();
d.Fly();

IWalkable walker = d;
walker.Walk();

ISwimmable swimmer = d;
swimmer.Swim();

Donald waddles along
Donald swims in the water
Donald flaps its wings and takes off
Donald waddles along
Donald swims in the water

interface ILogger
{
    void Log(string message);

    void LogWarning(string message)
    {
        Log($"[WARN] {message}");
    }

    void LogError(string message)
    {
        Log($"[ERROR] {message}");
    }
}

class ConsoleLogger : ILogger
{
    public void Log(string message)
    {
        Console.WriteLine(message);
    }
}

class SimpleLogger : ILogger
{
    public void Log(string message)
    {
        Console.WriteLine($">> {message}");
    }
}

ConsoleLogger cl = new ConsoleLogger();
cl.Log("System started");
cl.LogWarning("Low memory");
cl.LogError("Connection failed");

SimpleLogger sl = new SimpleLogger();
sl.Log("System started");
sl.LogWarning("Low memory");

System started
[WARN] Low memory
[ERROR] Connection failed
>> System started
>> [WARN] Low memory

interface IEnglish
{
    void Speak();
}

interface IFrench
{
    void Speak();
}

class BilingualPerson : IEnglish, IFrench
{
    void IEnglish.Speak()
    {
        Console.WriteLine("Hello!");
    }

    void IFrench.Speak()
    {
        Console.WriteLine("Bonjour!");
    }

    public void Speak()
    {
        Console.WriteLine("Hi!");
    }
}

BilingualPerson p = new BilingualPerson();
p.Speak();

IEnglish eng = p;
eng.Speak();

IFrench fr = p;
fr.Speak();

Hi!
Hello!
Bonjour!

class Student : IComparable<Student>
{
    public string Name { get; set; }
    public int Score { get; set; }

    public Student(string name, int score)
    {
        Name = name;
        Score = score;
    }

    public int CompareTo(Student other)
    {
        if (other == null) return 1;
        return Score.CompareTo(other.Score);
    }

    public override string ToString()
    {
        return $"{Name}({Score})";
    }
}

Student[] students = new Student[]
{
    new Student("Alice", 85),
    new Student("Bob", 92),
    new Student("Charlie", 78),
    new Student("Diana", 95),
    new Student("Eve", 88)
};

Console.WriteLine("Before sorting:");
foreach (var s in students)
    Console.WriteLine(s);

Array.Sort(students);

Console.WriteLine("After sorting (by score ascending):");
foreach (var s in students)
    Console.WriteLine(s);

Before sorting:
Alice(85)
Bob(92)
Charlie(78)
Diana(95)
Eve(88)
After sorting (by score ascending):
Charlie(78)
Alice(85)
Eve(88)
Bob(92)
Diana(95)