บทนำสู่พหุรูปแบบ

พหุรูปแบบคืออะไร

ทำความเข้าใจการเขียนทับเมธอด

using System;

class Animal {
    public virtual void Speak() {
        Console.WriteLine("The animal makes a sound.");
    }
}

class Dog : Animal {
    public override void Speak() {
        Console.WriteLine("The dog barks.");
    }
}

class Cat : Animal {
    public override void Speak() {
        Console.WriteLine("The cat meows.");
    }
}

class Program {
    static void Main() {
        Animal myDog = new Dog();
        Animal myCat = new Cat();

        myDog.Speak(); // Outputs: The dog barks.
        myCat.Speak(); // Outputs: The cat meows.
    }
}

การใช้พหุรูปแบบ

using System;

class Animal {
    public virtual void Speak() {
        Console.WriteLine("The animal makes a sound.");
    }
}

class Dog : Animal {
    public override void Speak() {
        Console.WriteLine("The dog barks.");
    }
}

class Cat : Animal {
    public override void Speak() {
        Console.WriteLine("The cat meows.");
    }
}

class Program {
    static void Main() {
        Animal[] animals = { new Dog(), new Cat() };

        foreach (Animal animal in animals) {
            animal.Speak(); // Calls the appropriate method for each object
        }
    }
}

การใช้คีย์เวิร์ดคลาสฐานร่วมกับการเขียนทับ

using System;

class Animal {
    public virtual void Speak() {
        Console.WriteLine("The animal makes a sound.");
    }
}

class Dog : Animal {
    public override void Speak() {
        base.Speak(); // Calls the base class method
        Console.WriteLine("The dog barks.");
    }
}

class Program {
    static void Main() {
        Dog myDog = new Dog();
        myDog.Speak(); // Outputs: The animal makes a sound. The dog barks.
    }
}

คลาสและเมธอดนามธรรม

using System;

abstract class Animal {
    public abstract void Speak(); // Abstract method
}

class Dog : Animal {
    public override void Speak() {
        Console.WriteLine("The dog barks.");
    }
}

class Program {
    static void Main() {
        Animal myDog = new Dog();
        myDog.Speak(); // Outputs: The dog barks.
    }
}

โจทย์ฝึกปฏิบัติ

using System;

abstract class Shape {
    public abstract double CalculateArea();
}

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

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

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

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

class Program {
    static void Main() {
        Shape rectangle = new Rectangle { Width = 4, Height = 5 };
        Shape circle = new Circle { Radius = 3 };

        Console.WriteLine("Rectangle Area: " + rectangle.CalculateArea());
        Console.WriteLine("Circle Area: " + circle.CalculateArea());
    }
}

แนวทางปฏิบัติที่ดีสำหรับพหุรูปแบบ

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