On Tue, 3 Feb 2004, wolski wrote:
> Hi!
>
> I try to pass a character by the .Call interface to an c function. And to
cast it into a
>
> char *ch;
>
> Is it possible to do it and how?
>
Yes. First make sure you have your "Writing R Extensions" handy. Next
decide whether you are going to use Rdefines.h or Rinternals.h. Then read
the chosen header file (in R/includes/). (Rdefines.h includes
Rinternals.h). For example line 255 in Rinternals.h gives
#define STRING_ELT(x,i) ((SEXP *) DATAPTR(x))[i]
I have used incantations like
CHAR(STRING_ELT(x, 0))
where x is a character vector - be prepared to use Rprintf() to check that
your assignment works out.
>
> Eryk
>
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--
Roger Bivand
Econonic Geography Section, Department of Economics, Norwegian School of
Economics and Business Administration, Breiviksveien 40, N-5045 Bergen,
Norway, voice: +47-55959355, fax: +47-55959393; Roger.Bivand at nhh.no