const-directive.md

title	#Const Directive
ms.date	07/20/2015
ms.prod	.net
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ms.technology	devlang-visual-basic
ms.topic	article
f1_keywords	vb.#Const #vb.Const #Const
helpviewer_keywords	#Const directive conditional compilation [Visual Basic], directives Const directive (#Const) Visual Basic compiler, compiler directives constants [Visual Basic], Const directive constants [Visual Basic], declaring Const statement [Visual Basic], directive (#Const) declaring constants [Visual Basic], #const directive
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#Const Directive

Defines conditional compiler constants for Visual Basic.

Syntax

#Const constname = expression  

Parts

constname
Required. Name of the constant being defined.

expression
Required. Literal, other conditional compiler constant, or any combination that includes any or all arithmetic or logical operators except Is.

Remarks

Conditional compiler constants are always private to the file in which they appear. You cannot create public compiler constants using the #Const directive; you can create them only in the user interface or with the /define compiler option.

You can use only conditional compiler constants and literals in expression. Using a standard constant defined with Const causes an error. Conversely, you can use constants defined with the #Const keyword only for conditional compilation. Constants can also be undefined, in which case they have a value of Nothing.

Example

This example uses the #Const directive.

[!code-vbVbVbalrConditionalComp#3]

See Also

/define (Visual Basic)
#If...Then...#Else Directives
Const Statement
Conditional Compilation
If...Then...Else Statement