How to: Declare Conditional Compilation Constants
You can set conditional compilation constants in one of three ways:
In the Project Designer
At the command line when using the command-line compiler
In your code
Conditional compilation constants have a special scope and cannot be accessed from standard code. The scope of a conditional compilation constant is dependent on the way it is set. The following table lists the scope of constants declared using each of the three ways mentioned above.
How constant is set
Scope of constant
Public to all files in the project
Public to all files passed to the command-line compiler
#Const statement in code
Private to the file in which it is declared
To set constants in the Project Designer
Before creating your executable file, set constants in the Project Designer by following the steps provided in How to: Modify Project Properties and Configuration Settings.
To set constants at the command line
Use the /d switch to enter conditional compilation constants, as in the following example:
vbc MyProj.vb /d:conFrenchVersion=–1:conANSI=0
No space is required between the /d switch and the first constant. For more information, see /define (Visual Basic).
Command-line declarations override declarations entered in the Project Designer, but do not erase them. Arguments set in Project Designer remain in effect for subsequent compilations.
When writing constants in the code itself, there are no strict rules as to their placement, since their scope is the entire module in which they are declared.
To set constants in your code
Place the constants in the declaration block of the module in which they are used. This helps keep your code organized and easier to read.