[R] Passing characters by .Call

[Wolski]

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