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The Object Class
Introduction to Object

In C# there is one type of reference that can be used for all objects. It’s aptly called Object.

Every class is derived from Object. Whether it’s the class’ superclass or the superclass’ superclass’ superclass, Object is at the top of the class’ inheritance hierarchy.

Since references can be upcast to any type in its inheritance hierarchy, then all types can by referenced as Objects:

Object o1 = new Dissertation(); Object o2 = new Diary(); Object o3 = new Random(); Object o4 = new Forest("Amazon");

If that’s so, why not use Object references for everything? Because the functionality of an object is limited by its reference type. We lose all of a specific type’s specific functionality when we reference it as an Object type. We would also lose the automatic type-checking that saves us from type errors.

When we do use them, Object references can be very useful! For example, if we’re not sure what type a variable is, we can safely store it as an Object. We can also assume that any object has access to the standard Object members for basic manipulation.

In this lesson, you’ll learn:

  • How every type inherits from Object
  • The useful members in Object

Instructions

In this inheritance diagram, we see that every type ultimately inherits from Object:

  • Random and Forest inherit directly from Object
  • Diary and Dissertation inherit from Book, which inherits from Object
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