Conference turris::fortran

1191.0. "'#' char in column 1 to allow use of C preprocessors" by CSC32::D_SANFORD () Thu Feb 20 1997 21:24

    Steve,

    "DEC Fortran For OpenVMS VAX CSCPAT_0402 V6.1-101 Fixes ECO Summary"
    says:

	V6.1-100 The compiler now accepts the '#' character in column
	1 as a whole-line comment delimiter. This is intended
	to allow the use of C preprocessors with Fortran
	source and use of '#' as a general comment delimiter
	is not recommended.

    We opened the door on this, now the customer asks:

	So, I need more details on the phrase "intended to allow 
	the use of C preprocessors with Fortran source".

	Are there any Fortran switches that allow the C preprocessor 
	to be run on Fortran source code with the results being 
	passed to the Fortran compiler?

	If this is true, we may want to use conditional compilation 
	to support both Windows NT and OpenVMS with the same Fortran 
	source code.

    Is the use of this documented anywhere?

    Thank you in advance, -drew



          <<< TURRIS::DISK$NOTES_PACK:[NOTES$LIBRARY]FORTRAN.NOTE;1 >>>
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Note 13.94                       DFVV bugs fixed                       94 of 159
QUARK::LIONEL "Free advice is worth every cent"       4 lines   4-FEB-1994 10:36
               -< # now allowed as comment introducer, V6.1-100 >-
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The compiler now accepts the '#' character in column 1
as a whole-line comment delimiter.  This is intended to allow the use of
C preprocessors with Fortran source and use of '#' as a general comment
delimiter is not recommended.

    No - the idea is that you would run C/PREPROCESS_ONLY (requiring that
    you have DEC C.)  Either that, or one of the various freeware
    implementations of cpp.
    
    We've kicked around the idea of building at least the conditional
    compilation (but not macro expansion) part of cpp into the compilers.
    The Fortran 90 compiler on Alpha actually has conditional compilation,
    but using Microsoft Fortran PowerStation syntax, not cpp. (And not
    documented except for the forthcoming Intel compiler, for now.)  
    Eventually, we may well add cpp syntax also, but right now the Fortran
    standards committee is waffling on what conditional compilation in
    Fortran should look like, and we may want to see what falls out.
    
    Maybe in the next year we'll actually get around to doing something
    here - even on VAX.
    
    					Steve

    I will pass that on.  So, you would use "CC/PREPROCESS_ONLY file.FOR"
    and take the resulting file "file.I" as input to the FORTRAN compiler.
    It all makes sense now...  Thank you.
    
    -drew

Yes.  However, the C preprocessor will mangle the program somewhat unless
you add /STANDARD=COMMON/COMMENTS=AS_IS to the CC/DECC/PREPROCESS_ONLY command
line. See TURRIS::DECC note 1889 for more information.

			Steve