[R] Passing characters by .Call
Wolski
wolski at molgen.mpg.de
Tue Feb 3 17:09:53 CET 2004
Hi!
Thank a lot!
Its what I was looking for.
Eryk.
*********** REPLY SEPARATOR ***********
On 2/3/2004 at 5:02 PM Roger Bivand wrote:
>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
Dipl. bio-chem. Eryk Witold Wolski @ MPI-MG Dep. Vertebrate Genomics
Ihnestrasse 73 14195 Berlin 'v'
tel: 0049-30-84131285 / \
mail: wolski at molgen.mpg.de ---W-W---- http://www.molgen.mpg.de/~wolski
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