Name
#Const Directive
Syntax
#Constconstantname = expression
-
constantname
Use: Required
Data Type: String literal
Name of the constant
-
expression
Use: Required
Data Type: Literal
Any combination of literal values, other conditional compilation constants defined with the
#Const
directive, and arithmetic or logical operators exceptIs
Description
Defines a conditional compiler constant.
By using compiler constants to create code blocks that are included in the compiled application only when a particular condition is met, you can create more than one version of the application using the same source code. This is a two-step process:
Defining the conditional compiler constant. This step is optional; conditional compiler constants that are not explicitly defined by the
#Const
directive, but are referenced in code, default to a value of Nothing.Evaluating the constant in the conditional compiler
#If...Then
statement block.
A conditional compiler constant can be assigned any string, numeric,
or logical value returned by an expression. However, the expression
itself can only consist of literals, operators other than
Is
, and another conditional compiler constant.
When the constant is evaluated, the code within the conditional
compiler #If...Then
block is compiled as part of
the application only when the expression using the conditional
compiler constant evaluates to True
.
Rules at a Glance
Conditional compiler constants are evaluated by the conditional compiler
#If...Then
statement block.You can ...
Get VB .NET Language in a Nutshell now with the O’Reilly learning platform.
O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.