IFNDEF

Begins block that will be compiled only if given macro isn't defined.

Syntax

IFNDEF Name [identifier]

Description

This directive begins block of code that will be allowed to pass to the compiler by the preprocessor only if macro with given name isn't defined. Otherwise lines below this will be skipped until corresponding ENDIF directive.

Example

DEFINE width 640

IFNDEF width
  ERROR "You have forgotten to define width!"
ENDIF