# -define (Visual Basic)

Defines conditional compiler constants.

## Syntax

-define:["]symbol[=value][,symbol[=value]]["]
' -or-
-d:["]symbol[=value][,symbol[=value]]["]


## Arguments

Term Definition
symbol Required. The symbol to define.
value Optional. The value to assign symbol. If value is a string, it must be surrounded by backslash/quotation-mark sequences (\") instead of quotation marks. If no value is specified, then it is taken to be True.

## Remarks

The -define option has an effect similar to using a #Const preprocessor directive in your source file, except that constants defined with -define are public and apply to all files in the project.

You can use symbols created by this option with the #If...Then...#Else directive to compile source files conditionally.

-d is the short form of -define.

You can define multiple symbols with -define by using a comma to separate symbol definitions.

To set /define in the Visual Studio integrated development environment
1. Have a project selected in Solution Explorer. On the Project menu, click Properties.
2. Click the Compile tab.
4. Modify the value in the Custom Constants box.

## Example

The following code defines and then uses two conditional compiler constants.

    ' Vbc /define:DEBUGMODE=True,TRAPERRORS=False test.vb
Sub mysub()
#If debugmode Then
' Insert debug statements here.
MsgBox("debug mode")
#Else
' Insert default statements here.
#End If
End Sub