Related items of information are often stored in multiple arrays (or in a multidimensional array). However, it is often preferable to store related data in a single array of structures. The Structure statement is often used to define a data structure capable of retrieving, storing, and saving fixed-length records. However, this is complicated by the absence of support for explicitly declared fixed-length strings in VB.NET. One solution is to use the attribute, where length is the fixed length of the string, when defining a member of type String. This instructs the VB .NET compiler to enforce a particular string length for the structure. For example: Structure Person Public FName As String Public MName As String Public LName As String Public Age As Short End Structure VB .NET/VB 6 Differences The Structure…EndStructure construct is new to VB .NET. It replaces the Type…EndType construct in VB 6. VB 6 user-defined types are different than VB .NET structures. A VB 6 user-defined type is simply a composite data type that combines multiple data types; it allows the user-defined type to be treated as a contiguous, word- or double-word aligned block of memory. A VB .NET structure is in some sense a hybrid object that combines data types and methods; ordinarily, no assumptions should be made about its layout in memory. In VB 6, the declaration of user-defined type members did not permit an access modifier. In VB .NET, it is required. Sub Statement Syntax [ClassBehavior] [AccessModifier] Sub name [(arglist)] [statements] [Exit Sub] [statements] End Sub ClassBehavior Use: Optional Type: Keyword One of the keywords shown in the following table: Keyword Description Overloads Indicates that more than one declaration of this subroutine exists (with different argument signatures). Overrides For derived classes, indicates that the subroutine overrides the subroutine by the same name (and argument signature) in the base class. Overridable Indicates that the subroutine can be overridden in a derived class. NotOverridable Indicates that the subroutine cannot be overridden in a derived class. MustOverride Indicates that the subroutine must be overridden in a derived class.
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