[R] Passing character strings from C code to R

mkondrin
Fri, 15 Jul 2005 15:32:03 -0000

Tuszynski, Jaroslaw W. wrote:

>Hi,
>
>I have a C code which produces array of integers and potentially a string,
>and I have problems passing the string out. Here is the relevant part of the
>code:
>
> 1   PROTECT(Ret = allocVector(INTSXP, n));
> 2   ret     = (int*) INTEGER(Ret);  /* get pointer to R's Ret */
> 3   for(i=0; i<n; i++) ret[i] = data[i];
> 4   Free(data);
> 5   i=1;
> 6   if (comment) { // comment was found
> 7     n = strlen(comment);
> 8     if(n>0) {    // and it actually have some length
> 9        Rprintf(" '%s' %i\n", comment, n);
> 10       PROTECT(Str = allocString(n+1));
> 11       str = CHAR(STRING_ELT(Str, 0));
> 12       strcpy(str, comment);
> 13       Rprintf(" '%s' %i\n", str, n);
> 14       setAttrib(Ret, install("comm"), Str);
> 15       i=2;
> 16     }
> 17     Free(comment);
> 18   }
> 20   UNPROTECT(i);
>
>Print statement in line 9 gives right results, but program crashes before
>print statement in line 13.
>Any ideas to what am I doing wrong?
>
>Jarek
>=====================================\====
> Jarek Tuszynski, PhD.                               o / \
> Science Applications International Corporation  <\__,|
> (703) 676-4192                        ">  \
> Jaroslaw.W.Tuszynski at saic.com                   `    \
>
>______________________________________________
>R-help at stat.math.ethz.ch mailing list
>https://stat.ethz.ch/mailman/listinfo/r-help
>PLEASE do read the posting guide!
http://www.R-project.org/posting-guide.html
>
>
SEXP charToSexp(char * val) {
  USER_OBJECT_ ans;
  PROTECT(ans = NEW_CHARACTER(1));
  if(val)
      SET_STRING_ELT(ans, 0, COPY_TO_USER_STRING(val));
  UNPROTECT(1);

  return(ans);
}