R help - May 2013 - Using as.integer(NA) in the .C function

Hi the list,
I am including some C code in a R program using the .C interface. I want to
deal with NA values, but the result is strange:

--- 8< ------------ C code -----------
void hein(int *a, int *b, int* c){
  *c = (*a + *b);
}
--- 8< -----------------------------------
--- 8< ------------- R code -----------
>
.C("hein",as.integer(NA),as.integer(1),as.integer(1),NAOK=TRUE)[[3]]
[1] -2147483647
--- 8< ---------------------------------
The result should be NA, isn't it? What wrong il my code?

Christophe



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On 07-05-2013, at 15:30, cgenolin <cgenolin at u-paris10.fr> wrote:
> Hi the list,
> I am including some C code in a R program using the .C interface. I want to
> deal with NA values, but the result is strange:
> 
> --- 8< ------------ C code -----------
> void hein(int *a, int *b, int* c){
>  *c = (*a + *b);
> }
> --- 8< -----------------------------------
> --- 8< ------------- R code -----------
>>
.C("hein",as.integer(NA),as.integer(1),as.integer(1),NAOK=TRUE)[[3]]
> [1] -2147483647
> --- 8< ---------------------------------
> The result should be NA, isn't it?
Why?
> What wrong il my code?

Read the manual "Writing R Extensions".
See section 5.10.3 and section 6.4 in that manual (I'm referring to the pdf
available on CRAN for R-3.0.0).
There may be more references in the manual but these were the first I found by
searching, which you should have done.

Berend