Shared Members. You can control whether a member of a class is a shared or instance member. Object Orientation. Classes are object-oriented, but modules are not. You can create one or more instances of a class. Feedback will be sent to Microsoft: By pressing the submit button, your feedback will be used to improve Microsoft products and services.
Privacy policy. Skip to main content. This browser is no longer supported. Download Microsoft Edge More info. Contents Exit focus mode. Is this page helpful? Yes No. Any additional feedback? Skip Submit. Submit and view feedback for This product This page. View all page feedback. See NotInheritable. The following code implements the Age property:. As you can see from the previous code, VB has a special syntax for defining the property accessors. As soon as we finish typing the line:. Note the Value parameter that provides access to the incoming value.
Thus, if we write:. The members of a class fall into two categories:. Members that can only be accessed through an instance of the class, that is, through an object of the class.
Members that can be accessed without creating an instance of the class. These members are shared among all instances of the class. More correctly, they are independent of any particular object of the class. Here is an example:. To access a shared member, we simply qualify the member with the class name. For instance, the String class in the System namespace of the. Its syntax in one form is:. This function returns 0 if the strings are equal, -1 if the first string is less than the second, and 1 if the first string is greater than the second.
Since the method is shared, we can write:. Shared members are useful for keeping track of data that is independent of any particular instance of the class.
For instance, suppose we want to keep track of the number of CPerson objects in existence at any given time. Then we write code such as the following:. Constructors can be used to initialize an object when necessary. We can define constructors in a class module. However, if we choose not to define a constructor, VB uses a default constructor.
For instance, the line:. To define a custom constructor, we just define a subroutine named New within the class module. For instance, suppose we want to set the Name property to a specified value when a CPerson object is first created. Then we can add the following code to the CPerson class:. Note that because VB. NET supports function overloading discussed later in this chapter , we can define multiple constructors in a single class, provided each constructor has a unique argument signature.
A program in VB. NET may also contain Modules and Namespaces. But the Class is the core unit—things like Strings and Lists are special classes. First example. This program introduces an Example Class. In the Class, we have a Private field of type Integer. We also have a constructor—the New Sub. Value Finally we have the Value Function, which returns an expression based on a field. It is Public, so can be called from Main. Step 1 In the Main Sub, control flow begins.
We create an instance of the Example Class—an Example now exists on the managed heap. Step 2 We access the Example instance called "x" and invoke its Value Function. This returns 2, and we print the result. Me qualifier. With the Me qualifier, we specify a member directly on the current instance of the class. If the class is derived, any further derived classes are ignored. Info With "Me," we can qualify whether we mean to indicate a local variable, or a member on the current class.
Here We use Me. The variable "species" is the parameter to the New Sub. With Inherits, one class can inherit from another class. This means it gains all the fields and procedures from the parent class. They provide their own constructors New. Download VB. Bulk Delete. Bulk Update. Bulk Merge. What is Class? You can use Class only at namespace or module level.
The declaration context for a class must be a source file, namespace, class, structure, module, or interface, and cannot be a procedure or block.
Rules Nesting: You can define one class within another. The outer class is called the containing class, and the inner class is called a nested class.
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