[R] passing char's from C to Fortran (mac os x)
Prof Brian Ripley
ripley at stats.ox.ac.uk
Mon Jul 5 16:43:14 CEST 2004
On Mon, 5 Jul 2004, Ingmar Visser wrote:
> Hello All,
> In some package I use a c-routine which calls a fortran routine which
> expects a char-string as input.
> As per the writing R-extensions manual,
> the Fortran routine is declared in C as:
> void F77_NAME (setoptions) (char **option);
That's not in that manual. It says
The following table gives the mapping between the modes of R vectors and
the types of arguments to a C function or FORTRAN subroutine.
and not between the latter two.
> and then it is calles as follows:
> char **option;
> option = new char*;
> option = new char;
> option = strcpy(option,"Iteration Limit = 100");
> F77_CALL (setoptions) (option);
> Unfortunately this does not work, ie the fortran routine setoptions does
> not correctly get the intended character string. Can anyone point me to a
> working example of passing characters from C to Fortran? Or tell me what's
> wrong in my code above?
It's not C! (It looks like C++.) Where did you get the idea that Fortran
character corresponds to char** in C? It probably corresponds to char*,
possibly with a length passed separately. Since you are probably using
g77 I expect passing char * from C to Fortran will work, but passing back
R is a C program and it manages to pass characters to Fortran in quite a
few places, such as Lapack.c and loessc.c/loessf.f.
Brian D. Ripley, ripley at stats.ox.ac.uk
Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/
University of Oxford, Tel: +44 1865 272861 (self)
1 South Parks Road, +44 1865 272866 (PA)
Oxford OX1 3TG, UK Fax: +44 1865 272595
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