VB.NET is an Object Oriented programming language. The Objects referred to are created from something called a Class. You've already used Classes throughout this course. But we'll now have a closer look at them.
Object Oriented programming
The modern trend in programming languages is for code to be separated into chunks. When it's being used, each chunk of code (a chunk of code that opens text files, for example) is known as an Object. The code for the Object can then be reused whenever it is needed. Languages like C++ and Java are Object Oriented languages. Until Microsoft came out with VB.NET, the Visual Basic programming language was not OOP (object oriented programming). This time it is.
Object Oriented programming has a steeper learning curve, and things like Encapsulation, Inheritance and Polymorphism have to be digested. We're not going quite that far in this beginner's course. But you should have a good, basic understanding of just what Object are by the end of this section, and how to create your own Objects.
Classes and Objects
In VB.NET, a class is that chunk of code mentioned earlier. You've been using Classes all the time during this course. The Form you've started out with is a Class. If you look right at the top of the code window for a Form, you'll see:
Public Class Form1
The word "Public" means that other code can see it. Form1 is the name of the Class
If you look at the bottom of the coding window, you'll see End Class, signifying the end of the code for the Class.
When you place a Button or a textbox on the Form, you're really adding it to the Form Class.
When you start the Form, VB does something called instantiation. This basically means that your Form is being turned into an Object, and all the things needed for the creation of the Form are being set up for you (Your controls are being added, variables are being set up an initialised, etc).
And that's the basic difference between a Class and an Object: A Class is the code itself; the code becomes an Object when you start using it.
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