[R] Passing character strings from C code to R

[Prof Brian Ripley]

Why invent your own function to do the same thing as the builtin 
one mkString?

Please discuss C programming questions on the R-devel list *as the posting 
guide asks*

On Fri, 15 Jul 2005, mkondrin wrote:

> 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);
> }
>
> ______________________________________________
> 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
>

-- 
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