[Rcpp-devel] short, unsigned short, long, unsigned long, long double

[Douglas Bates]

On Tue, Apr 6, 2010 at 8:40 AM, Romain Francois
<romain at r-enthusiasts.com> wrote:
> Le 06/04/10 15:32, Dirk Eddelbuettel a écrit :
>>
>> On 6 April 2010 at 14:27, Romain Francois wrote:
>> |>  Perhaps I am not answering the question that you asked - that sort of
>> |>  thing happens when answering email while still on the first cup of
>> |>  coffee.  More helpful might be the comments in the limits include file
>> |>  for libstdc++ on Debian/Ubuntu
>> |>
>> |>  // The numeric_limits<>   traits document implementation-defined
>> aspects
>> |>  // of fundamental arithmetic data types (integers and floating
>> points).
>> |>  // From Standard C++ point of view, there are 13 such types:
>> |>  //   * integers
>> |>  //         bool
>> (1)
>> |>  //         char, signed char, unsigned char                 (3)
>> |>  //         short, unsigned short                            (2)
>> |>  //         int, unsigned                                    (2)
>> |>  //         long, unsigned long
>>  (2)
>> |>  //
>> |>  //   * floating points
>> |>  //         float                                            (1)
>> |>  //         double                                           (1)
>> |>  //         long double
>>  (1)
>> |>  //
>> |>  // GNU C++ understands (where supported by the host C-library)
>> |>  //   * integer
>> |>  //         long long, unsigned long long                    (2)
>> |>  //
>> |>  // which brings us to 15 fundamental arithmetic data types in GNU C++.
>> |>
>> |>  So it looks like short is part of standard C++ but not long long.
>> |
>> | Even better, thanks again.
>>
>> Not to beat a dead horse (and yours, at that) but the long long and
>> unsigned
>> long long are hence not portable but GNU g++ dependent.
>
> I have not touched long long and unsigned long long so we are still in
> standard c++.
>
> If I do them, they will be hidden in #ifdef __GNUC__

What do you plan to do about wrapping a std::vector<long double>?
There is no corresponding data type in R.  With something like long
long you can map to a double which takes most of the range without
round-off but a long double will either be truncated by mapping to a
double or will need some crafty construction in R.