On Mon, Jun 7, 2010 at 8:38 PM, Martin Simmons <martin@lispworks.com> wrote:

>>>>> On Mon, 7 Jun 2010 11:12:47 -0600, Mark Hoemmen said:
>
> On Mon, Jun 7, 2010 at 10:56, Martin Simmons <martin@lispworks.com> wrote:
> >>>>>> On Sat, 5 Jun 2010 16:12:58 +0200, Juan Jose Garcia-Ripoll said:
> >>
> >> CHARACTERs in Fortran are just pointers of type char*, just like in C, and
> >> just like any other fortran array. There is no terminating null and the
> >> fortran functions get the length either from some argument or because they
> >> assume a given size (for instance in Lapack it is a one-character string
> >> what the function expects)
> >
> > Are you sure about? I think the lengths are passed as implicit arguments at
> > the end of the argumwnt list.
>
> Not on any Fortran compilers I've seen, at least when dealing with
> LAPACK. Replacing CHARACTER*(*) with "char* const" when calling
> LAPACK routines that take CHARACTER*(*) arguments works perfectly fine
> with all the Fortran compilers I've encountered (e.g., gfortran, Intel
> Fortran compiler, IBM's xlf).

Maybe LAPACK is compiled with options that make this work (or nothing looks at
the length arguments), but when I compile the code below with gfortran it
clearly passes the string lengths 4 and 3 as extra arguments.

INTEGER FUNCTION ILAENV( NAME , NN )
CHARACTER*( * ) NAME, NN
ILAENV = ICHAR( NAME( 1: 1 ) )
RETURN
END

INTEGER FUNCTION ZZZ( )
ZZZ = ILAENV("fooo", "bar")
RETURN
END

movl $3, %ecx
movl $4, %edx
movl $.LC0, %esi
movl $.LC1, %edi
call ilaenv_

--
Martin Simmons
LispWorks Ltd
http://www.lispworks.com/

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