The only element that interrupts the symmetry of the three forms is the statement: Dim myString As String. That has to do with a Structure being a "composite data type" as Microsoft states in their definition. Another thing to notice is that all three blocks have a Sub Main in them. One of the most fundamental principals of OOP is usually called encapsulation. This is the "black box" effect.
In other words, you should be able to treat each object independently and that includes using identically named subroutines if you want to. Classes are the 'right' place to start because, as Microsoft notes, "A class is a fundamental building block of object-oriented programming OOP.
A class is more object oriented than a module because it's possible to instantiate make a copy of a class but not a module. In other words, you can code The class instantiation is emphasized. It doesn't matter whether the actual class itself, in this case, The program runs exactly the same way.
Notice that Form1 is a class too. You can also write class code that behaves much like a module, that is, without instantiating it.
This is called a Shared class. NET explains this in much more detail. Another fact about classes should also be kept in mind. Members properties and methods of the class only exist while the instance of the class exists. The name for this is scoping.
That is, the scope of an instance of a class is limited. The code above can be changed to illustrate this point this way:. When the second myNewClass. In VB 6, it was common to see programs where most of the code was in a module A. BAS , file rather than, for instance, in a Form file such as Form1. In VB. NET, both modules and classes are in.
VB files. The main reason modules are included in VB. NET is to give programmers a way to organize their systems by putting code in different places to fine tune the scope and access for their code.
That is, how long members of the module exist and what other code can reference and use the members. Sometimes, you may want to put code into separate modules just to make it easier to work with. All VB. NET modules are Shared because they can't be instantiated see above and they can be marked Friend or Public so they can be accessed either within the same assembly or whenever they're referenced.
Structures are the least understood of the three forms of objects. If we were talking about "animals" instead of "objects," the structure would be an Aardvark.
The big difference between a structure and a class is that a structure is a value type and a class is a reference type. What does that mean? I'm so glad you asked. A value type is an object that is stored directly in memory. An Integer is a good example of a value type. This does not require any change in the For Each loop, i. Print automatically calls the right Print method the first one for "normal" persons and the second one for employees. There is much more to say about classes.
I hope that you got a certain idea of what you can do with classes. See Objects and classes in Visual Basic and especially the section Differences between classes and modules. A module is nothing more than another name for a static class. That's all there is to it. If you don't believe it, compile a module with VB. And yes, that means you're correct, in terms of functionality, a module is a SUBset of a class. A class is more of a unit, and a module is essentially a loose collection of stuff like functions, variables, or even classes.
In a public module, classes in the project have access to the functions and variables of the module. You don't have to specify the module name to address one. You can also have classes in a module. The variables and functions of a class are under tighter "ownership" by the class. Public variables and functions methods used by other classes are used with the classname: classname. There is only one instance of a module, but a one or more instances of a class can be used at once.
The main difference between classes and modules is that classes can be instantiated as objects while standard modules cannot. Because there is only one copy of a standard module's data, when one part of your program changes a public variable in a standard module, any other part of the program gets the same value if it then reads that variable. In contrast, object data exists separately for each instantiated object.
Another difference is that unlike standard modules, classes can implement interfaces. Actually, you use classes to create objects. For example in the following. NET console application r is a Rectangle object:.
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Learn more. What is the difference between a module and a class? Ask Question. One module per class, bad idea? A simple question: What is the difference between a Module and a Class Module? And Office Help system. What is JavaScript? Web Applications. Microsoft Excel. How to implement control array with vba. The research path of clustering. Learn to programme How to Convert Text Dates to Date format.
Storing session info in Local Storage? Follow us! Get the Latest Bytes Updates. By using this site, you agree to our Privacy Policy and Terms of Use. Module and Class Laserson Hi! Jan 12 '06 Carlos J. Jan 12 '06 Herfried K.
Jan 12 '06 David Anton No - if you specify "Public" it still can't be accessed outside of the project - so for modules "Public" means the same as "Friend". Jan 12 '06 Dennis Interesting discussion Jan 13 '06 David Anton Others can outline the other reasons, but personally I don't like the way that modules hide their special characteristics. Cor Jan 13 '06 This discussion thread is closed Start new discussion Replies have been disabled for this discussion.
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