Visual Basic data structures: objects, types, enumerations

Enumerations

Enumerations are Visual Basic data types which hold sets of integer constants. Enumerations are useful to define family of constants to be used by the developers (i.e. options).

Refer Enumerations article for more information about enumerators.

Enumerators are treated as any other data types and can be declared and assigned. Enumerations can be assigned implicitly and explicitly.

Dim myEnumVal As MyEnum_e
Dim myEnumVal1 As MyEnum_e
myEnumVal = MyEnum_e.Val1 'assigning the enumerator explicitly stating the name of enumerator
myEnumVal1 = Val1 'implicit assignment of the enumerator

Type

Visual Basic allows to create new data groups. Custom user-defined Type is a data type, also known as Structure which allows to define complex data storage. Types are useful when it is required to pass or store the data which consists of multiple elements (e.g. geometrical point, log entry, etc.)

Refer Custom User Defined Types article for more information about custom types.

Class

Unlike enumerations and types classes can only be created in separate Visual Basic class modules.

Classes are reference types and must be initiated with new keyword and reference must be assigned using Set keyword.

Refer Classes article for more information about classes.

Code example below shows how to declare and assign enumerator, type and class.

Class declaration

Public Member As String

Private Sub Class_Initialize()

End Sub

Module

Enum MyEnum_e
    Val1 = 0
    Val2 = 1
    Val3 = 3
End Enum

Type MyStruct
    Field1 As String
    Field2 As Boolean
End Type    

Sub main()

    Dim enumVar As MyEnum_e
    enumVar = Val2
    
    Dim typeVar As MyStruct
    typeVar.Field1 = "Hello World"
    
    Dim classVar As MyClass
    Set classVar = New MyClass
    classVar.Member = "Hello World"

End Sub