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Anonymous · Guest

Hello,

Can somebody please help me with the following simplified piece of code?

PROGRAM TEST
IMPLICIT NONE

#define x

#ifdef x
PRINT*, 'ifdef works...'
#endif

#ifndef x
PRINT*, 'ifndef works...'
#endif

STOP
END PROGRAM TEST

It's the first time I'm trying to do something with preprosessor options and it doesn't work.
I'm compiling the program with "FTN95 TEST.F95 /CFPP" on the command line, with no errors, but on execution of the program NOTHING is printed to the screen.

So, I'm wondering was I'm doing wrong.

Kind regards

PaulLaidler · Posted: Mon Aug 21, 2006 1:18 am Post subject: Conditional compilation

Lucas

The #define and #ifdef work OK for me but #ifndef and the associated code is ignored.
At first sight there is something wrong with #ifndef. If it is not implemented by FTN95 then an error should be flagged.

I do not think that the outcome will depend on the version number of FTN95 because the feature was only added at about version 4.8 and to my knowledge there have been no changes made.

Are you sure you are not getting the first PRINT statement? Have you tried running from a DOS box?

The more common usage is to provide a value for the "SPECIAL PARAMETER" via the FTN95 command line so you may get better results this way.

Anonymous · Guest

Paul,

Thanks for your reply, I am a step further now.
This time I tried the following code:

PROGRAM TEST
IMPLICIT NONE
INTEGER :: I = 0
#define x
#ifdef x
I = 1
#endif
#ifndef x
I = 2
#endif
WRITE(6,*) I
END PROGRAM

and ran it from a DOS-box. The result was 2.
I did expect a 1 however, so now is my question: where can I find more detailed info about compiler directives such as #define, #ifdef and #ifndef,...? Because the help file doesn't tell me that much in this case.

Regards, Lucas.

Anonymous · Guest

Addendum:

I had better tried this first before posting:

PROGRAM TEST
IMPLICIT NONE
INTEGER :: I = 0

#define x

#ifdef x
I = 1
WRITE(6,*) I
#endif

#ifndef x
I = 2
WRITE(6,*) I
#endif

END PROGRAM

The resulting output is
1
2

So it seems that the "variable" x is at the time defined and undefined?
Very strange.

PaulLaidler · Posted: Mon Aug 21, 2006 5:31 am Post subject: Conditional compilation

Lucas

As I tried to say, #ifndef does not appear to be implemented in FTN95 and FTN95 should give an error report when an attempt is made to use #ifndef.

Avoid using #ifndef.

PaulLaidler · Posted: Tue Aug 22, 2006 9:54 am Post subject: Conditional compilation

Lucas

#ifndef has now been fixed for the next release of FTN95.