5.2.2 #IFNDEF

Syntax:

Lines following #IFNDEF are read only if the keyword name following it is not defined.

They are read until the keywords #ELSE or #ENDIF are encountered, after which normal processing is resumed.

Example :

In the above example, /usr/lib/fpc/2.2.0/linuxunits will be added to the path if you’re NOT compiling with version 2.2.0 of the compiler.