Appendix B

Variable Declarations and Data Types

This appendix provides information about variable declarations and data types.


The following code shows a standard variable declaration:

[attribute_list] [accessibility] [Shared] [Shadows] [ReadOnly] _
Dim [WithEvents] name[?] [(bounds_list)] [As [New] type[?]] _
[= initialization_expression]

The following list describes the pieces of this declaration:

  • attribute_list — Comma-separated list of attributes specific to a particular task. For example, <XmlAttributeAttribute(AttributeName:="Cost")>.
  • accessibility — Public, Protected, Friend, Protected Friend, Private, or Static.
  • Shared — Means that all instances of the class or structure containing the variable share the same variable.
  • Shadows — Indicates that the variable hides a variable with the same name in a base class.
  • ReadOnly — Indicates that the program can read, but not modify, the variable’s value. You can set the value in an initialization statement or in an object constructor.
  • Dim — Officially tells Visual Basic that you want to create a variable. You can omit the Dim keyword if you specify Public, Protected, Friend, Protected Friend, Private, Static, or ReadOnly.
  • WithEvents — Tells Visual Basic that the variable is of a specific object type that can raise events that you may want to catch.
  • name — Gives the name of the variable.
  • ? — Indicates this should be a nullable variable. For more information, see the section “Nullable Types” in Chapter 14, “Data ...

Get Visual Basic 2012 Programmer's Reference now with O’Reilly online learning.

O’Reilly members experience live online training, plus books, videos, and digital content from 200+ publishers.