Question

If I have a method that takes any object as a parameter I will like to create another object of the same type. In other words if I have an object of type Person I will like to cast or instantiate a new object of type person. If that object is an Animal in the other hand I will like to instantiate a new object from that class. All this without using an if or switch statement. let me show you what I mean

   class Animal {

        public virtual void Talk()
        {
            Console.WriteLine("-");
        }
    }
    class Dog :Animal
    {
        public override Talk()
        {
            Console.WriteLine("Woof");
        }
    }
    class Cat : Animal
    {
        public override void Talk()
        {
            Console.WriteLine("Miau");
        }
    }

    public static void Main(String[] args)
    {

        Animal a = generateRandomAnimal();

        Animal b;  // I want to institate object b without needing an if statement or a switch            


        // I want to avoid this...
        if (a is Dog)
            b = new Dog();
        else if (a is Cat)
            b = new Cat();
        else
            b = new Animal();

        // if I new what b would be a Cat in advance i know I could do :

        b = (Cat)b; 


        // if am looking for something like

        b=(a.GetType())b; // this gives a compile error

    }

    static Animal generateRandomAnimal()
    {
        switch (new Random().Next(1, 4))
        {
            case 1:
                return new Animal();
            case 2:
                return new Dog();
            default:
                return new Cat();
        }            
    }

Edit

Thanks to kprobst I ended up with:

    class Person
    {

        public string Address { get; set; }
        public string Name { get; set; }

    }

    class Animal
    {
        public virtual void Talk()
        {
            Console.WriteLine("-");
        }
    }

    class Car
    {
        public int numberOfDoors { get; set; }
    }


    static object generateRandomObject()
    {
        switch (new Random().Next(1, 4))
        {
            case 1:
                return new Person();
            case 2:
                return new Car();
            default:
                return new Animal();
        }
    }

    public static void Main(String[] args)
    {

        object o = generateRandomObject();

        object newObject;  // i want new object to be of the same type as object o


        if (o is Animal)
            newObject = new Animal();
        if (o is Person)
            newObject = new Person();
        if (o is Car)
            newObject = new Car();


        Type t = o.GetType();
        var b = Activator.CreateInstance(t);
        //.....etc

In my example not all objects inherited from the same class. It is the first time I see the a real benefit from the var keword. I know it is helpful but I just have use it to make my code smaller and more readable… but in this case it really helps out!

Answer 1

Something like this:

Type t = a.GetType();
Animal b = (Animal) Activator.CreateInstance(t);

(didn’t actually test that)