Upcasting

The assignment of child class object to a parent class reference in C# inheritance is known as up-casting.

Syntax
parentClass objectName = new childClass();

CODE

EG 1 . Creating a child class, parent class and using Upcasting

class Rectangle2D {
    public double length, width;
    public double Area() {
        return length * width;
    }
    public double Perimeter() {
        return 2 * (length+width);
    }
}

class Rectangle3D : Rectangle2D {
    public double height;
    public double Volume() {
        return length * width * height;
    }
}

class Program {
    static void Main() {
        //Upcasting
        Rectangle2D r1 = new Rectangle3D();
    }
}

CODE EXPLANATION
In the above code, we created a new child class object (Rectangle3D) and assigned that to Parent class (Rectangle2D) reference called r1. This assignment of child class object to a parent class reference in C# inheritance is known as up-casting.


What is the use of Upcasting?
We going to study an important topic is OOPs called Abstraction(Next Article). Abstraction is not possible without Upcasting. Upcasting plays important role in Abstract classes and Interfaces.