[Rd] wchar and wstring.
Prof Brian Ripley
ripley at stats.ox.ac.uk
Sat Aug 27 13:33:15 CEST 2005
On Fri, 26 Aug 2005, James Bullard wrote:
> Hello all, I am writing an R interface to some C++ files which make use
> of std::wstring classes for internationalization. Previously (when I
> wanted to make R strings from C++ std::strings), I would do something
> like this to construct a string in R from the results of the parse.
> SET_VECTOR_ELT(vals, i++, mkString(header.GetHeader().c_str()));
That creates a list of one-element character vectors. It would be more
usual to do
SET_STRING_ELT(vals, i++, mkChar(header.GetHeader().c_str()));
> However, now the call header.GetHeader().c_str() returns a pointer to an
> array of wchar_t's. I was going to use wcstombs() to convert the
> wchar_t* to char*, but I wanted to see if there was a similar function
> in R for the mkString function which I had initially used which deals
> with wchar_ts as opposed to chars.
No (nor an analogue of mkChar). R uses MBCS and not wchar_t internally
(and Unix-alike systems do externally). There is no wchar_t internal R
type (a much-debated design decision at the time).
> Also, since I have no experience with the wctombs() function I wanted to
> ask if anyone knew if this will handle the internationilzation issues
> from within R.
Did you mean wcstombs or wctomb (if the latter, wcrtomb is preferred)?
There are tens of examples in the R sources for you to consult.
Note that not all R platforms support wchar_t, hence this code is
surrounded by #ifdef SUPPORT_MBCS macros (exported in Rconfig.h for
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
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