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

[Romain Francois]

Le 06/04/10 14:15, Douglas Bates a écrit :
> On Tue, Apr 6, 2010 at 6:54 AM, Romain Francois
> <romain at r-enthusiasts.com>  wrote:
>> Hello,
>>
>> I have added support for these primitive types in Rcpp, so that one can
>> wrap containers such as :
>>
>> std::vector<short>, ...
>>
>> Is this something that should be protected in case there is no "short",
>> "long", etc ?
>
> You can check in R's .Machine object on the various sizes for which R
> scans.  It can tell you if there is a difference between long and long
> long or between double and long double.  It does not list anything
> regarding short.  The sum of double.digits and double.exponent is the
> number of bits in a double.  Generally log(.Machine$integer.max, 2) is
> 1 less than the number of bits in an int.
>
>
>> str(.Machine)
> List of 18
>   $ double.eps           : num 2.22e-16
>   $ double.neg.eps       : num 1.11e-16
>   $ double.xmin          : num 2.23e-308
>   $ double.xmax          : num 1.80e+308
>   $ double.base          : int 2
>   $ double.digits        : int 53
>   $ double.rounding      : int 5
>   $ double.guard         : int 0
>   $ double.ulp.digits    : int -52
>   $ double.neg.ulp.digits: int -53
>   $ double.exponent      : int 11
>   $ double.min.exp       : int -1022
>   $ double.max.exp       : int 1024
>   $ integer.max          : int 2147483647
>   $ sizeof.long          : int 4
>   $ sizeof.longlong      : int 8
>   $ sizeof.longdouble    : int 12
>   $ sizeof.pointer       : int 4
>> log(.Machine$integer.max, 2)
> [1] 31

Ah yes, thanks. I guess I can pull some of this out the Rconfig.h where 
I see this for example:

/* Define if you have the 'long double' type. */
#undef HAVE_LONG_DOUBLE

No sign of short there either.

-- 
Romain Francois
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http://romainfrancois.blog.free.fr
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