c#:虚方法

using System;

public class Animal
{
    // 声明一个虚方法
    public virtual void Speak()
    {
        Console.WriteLine("Animal speaks");
    }
}

public class Dog : Animal
{
    // 重写基类的虚方法
    public override void Speak()
    {
        Console.WriteLine("Dog barks");
    }
}

public class Cat : Animal
{
    // 重写基类的虚方法
    public override void Speak()
    {
        Console.WriteLine("Cat meows");
    }
}

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

        myAnimal.Speak(); // 输出: Animal speaks
        myDog.Speak();    // 输出: Dog barks
        myCat.Speak();    // 输出: Cat meows
    }
}