Re: [Rd] How to convert time_t to R date object

[Sandip Nandi]

Hi Bill ,

The following C code  may help you , time_t is typedef to long int

SEXP  getTime() {

  time_t current_time;
    char* c_time_string;
    current_time = time(NULL);
    c_time_string = ctime(&current_time);

   return mkString(c_time_String); // or if you want to return as int
vector return scalarInt(current_time);
}

If you feel anything wrong , I will be very happy to know .

Thanks,
Sandip


On Sun, Mar 16, 2014 at 9:54 PM, Bill Wang <freecn...@gmail.com> wrote:

> Hi Dirk,
>
> Thanks for your reply, I neede convert time_t to R type in C code, can not
> use Rcpp. Maybe Rcpp source code could help me.
>
> Cheers,
> Bill
>
>
> 2014-03-16 22:55 GMT+08:00 Dirk Eddelbuettel <e...@debian.org>:
>
> >
> > On 16 March 2014 at 18:36, Bill Wang wrote:
> > | I am writing a R extensions, and I need pass time_t to R in C, but I
> > don't
> > | know how to do.
> > | Can you give me some help? do not use double directly.
> >
> > Just treat it as an int:
> >
> >   R> library(Rcpp)
> >   R> cppFunction("Date time_t2date(time_t what) { return((int) what); }")
> >   R> time_t2date(0)
> >   [1] "1970-01-01"
> >   R> time_t2date( Sys.Date() )
> >   [1] "2014-03-16"
> >   R>
> >
> >
> > Here I use Rcpp to define the 'time_t2date' function on the fly.
> >
> > It takes the time_t and returns a Date type (which here is a C++ Date
> type
> > mapping to the R Date -- you can ignore that, but will have to write the
> > legwork yourself if you don't use Rcpp).
> >
> > As 'time_t' is 'long int' on my system, so I cast it to int. The rest is
> > automagic (thanks to RcpP).
> >
> > Notice that I also get today's date down and up correctly.
> >
> > See 'Writing R Extensions' for the details at the C level.
> >
> > See the Rcpp documentation (and, if I may, my book) for details on Rcpp
> if
> > that interests you.
> >
> > Dirk
> >
> > --
> > Dirk Eddelbuettel | e...@debian.org | http://dirk.eddelbuettel.com
> >
>
>
>
> --
>
> *Travel | Programming*
> *http://freecnpro.net* <http://freecnpro.net>
>
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>
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