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Thread Tools Show Printable Version. Jun 24th, , PM 1. Difference between Class and module vb. Add a Solution. Top Rated Most Recent. Accept Solution Reject Solution. Then your google-fu needs some attention: difference between Module and class in vb. Posted Jun am OriginalGriff. Module is VB's version of a C static class. If you want to prevent object instantiation then use a Module, other wise use a Class: Classes vs. Modules in VB.
Posted Jun am Andy Lanng. Richard Deeming Jun pm. NET can be accessed without specifying the module name, for backwards-compatibility with VB6. Andy Lanng Jun am. Always keep the non-constant fields private. When you want to make it public, use a property instead. A method is an action that an object can perform. For example, Add is a method of the ComboBox object that adds a new entry to a combo box. The following example demonstrates the Start method of a Timer object.
An event is an action recognized by an object, such as clicking the mouse or pressing a key, and for which you can write code to respond. Events can occur as a result of a user action or program code, or they can be caused by the system.
Code that signals an event is said to raise the event, and code that responds to it is said to handle it. You can also develop your own custom events to be raised by your objects and handled by other objects.
For more information, see Events. When you create an object from a class, the result is an instance of that class. Members that are not declared with the Shared keyword are instance members , which belong strictly to that particular instance. An instance member in one instance is independent of the same member in another instance of the same class.
An instance member variable, for example, can have different values in different instances. Members declared with the Shared keyword are shared members , which belong to the class as a whole and not to any particular instance. A shared member exists only once, no matter how many instances of its class you create, or even if you create no instances. A shared member variable, for example, has only one value, which is available to all code that can access the class. In the statement that accesses the member, follow the object variable name with the member-access operator.
Follow the class name with the member-access operator. You should always access a Shared member of the object directly through the class name. If you have already created an object from the class, you can alternatively access a Shared member through the object's variable.
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. If a class is marked with the MustInherit modifier, it can't be instantiated directly. However, it's still different from a module as it can be inherited while modules can't be inherited. When the Shared modifier is applied to a class member, it is associated with the class itself instead of a particular instance of the class. The member is accessed directly by using the class name, the same way module members are accessed.
Classes and modules also use different scopes for their members. Members defined within a class are scoped within a specific instance of the class and exist only for the lifetime of the object.
To access class members from outside a class, you must use fully qualified names in the format of Object. On the other hand, members declared within a module are publicly accessible by default, and can be accessed by any code that can access the module. This means that variables in a standard module are effectively global variables because they are visible from anywhere in your project, and they exist for the life of the program.
Objects let you declare variables and procedures once and then reuse them whenever needed. 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. If you declared an Integer in your program like this You also see this described as "being allocated on the stack". The stack and the heap are simply different ways of managing the use of computer memory. A reference type is an object where the location of the object is stored in memory. So finding a value for a reference type is always a two step lookup.
A String is a good example of a reference type. If you declared a String like this You would have to go to that location to find the value "This is myString". This is often called "being allocated on the heap". The stack and the heap.
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