When you ask the programming language to create an instance of a specific class, something happens under the hood. The programming language runtime creates a new instance of the specified type, allocates the necessary memory, and then executes the code specified in the constructor. When the runtime executes the code within the constructor, there is already a live instance of the class. Thus, you have access to the attributes and methods defined in the class. However, as you might have guessed, you must be careful with the code you put within the constructor, because you might end up generating large delays when you create instances of the class.

So, for example, before you can call the CalculateArea method, you want the Width and Height attributes for each new Rectangle instance to have a value initialized to 0. Constructors are extremely useful when...