FORTRAN Reference Manual

Compiler Directives
FORTRAN Reference Manual—528615-001
10-38
IFNOT Compiler Directive
•
Once you have initiated skipping of source text using an IFNOT directive, source
lines are skipped until the next matching ENDIF. Thus, the way to write an if-then-
else decision structure is:
?IF n
(statements to be compiled if toggle n is set)
?ENDIF n
?IFNOT n
(statements to be compiled if toggle n is reset)
?ENDIF n
•
The compiler prints source lines skipped as a result of an IFNOT directive in the
source text listing with a “#” character to the left of the line.
Example
In the following example, the RESETTOG directive instructs the compiler to compile
code C. If you use a RESETTOG 2 and RESETTOG 3 directive, FORTRAN compiles
both code A and code B.
?RESETTOG 3
?IFNOT 2
code B
?ENDIF 2
?IFNOT 3
code C
?ENDIF 3