/define (Visual Basic)
Defines conditional compiler constants.
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
Have a project selected in Solution Explorer. On the Project menu, click Properties. For more information, see.
Click the Compile tab.
Modify the value in the Custom Constants box.