[R] Problem with .C

[Grigory Alexandrovich]

Hello,

first thank you for your answers.

I did not read the whole pdf Writing R Extension, but I read this 
strongly shortened introduction to this subject:

http://www.math.kit.edu/stoch/~lindner/media/.c.call%20extensions.pdf

I get the same error with this C-function:

void test(double * b, int l)
{
      int i;
      for(i=0; i < l ; i++) b[i] +=i;
}



I call it from R like this:

parameter = c(0,0,1,1,1,0,1.5,0.7,0,1.2,0.3);
.C("test", as.double(parameter), as.integer(11))

The programm crashes even in this simple case.
Where can be the error?

Thanks
Grigory Alexandrovich







Answer 1
> Without knowing that C code, we cannot know. Have you read Writing R Extensions carefully? I.e. take care with memory allocation and printing as mentioned in the manual.
>
> Uwe Ligges


Answer 2
> This looks like a classic case of not reading the manual, and then compounding it by not reading the posting guide. The manual would be the "Writing R Extensions" pdf that comes with R or you can google it. The posting guide is referenced at the bottom of this and every other posting on this mailing list.
> There are nearly an infinite variety of errors that can lead to a "crash", so it is really unreasonable of you to pose this question this way and expect constructive assistance.
> ---------------------------------------------------------------------------
> Jeff Newmiller The ..... ..... Go Live...
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Answer 3

> It's impossible to say, with such minimal information, but a reasonable
> guess is that there is a problem with the declaration of "x" and "y" in
> foo.c.  These would (I think) need to be declared as double *, not double,
> when foo is called from .C().
>
>     cheers,
>
>         Rolf Turner


Answer 4

> Hi,
>
> As other have said, it's very difficult to help you without an example
> + code to know what you are talking about.
>
> That having been said, it seems as if you are just getting your feet
> wet in this R <--> C bridge, and I'd recommend you checkout the "Rcpp"
> and "inline" package to help make your life a lot easier ...
>
> -steve








> On 04.10.2011 14:04, Grigory Alexandrovich wrote:
>> Hello,
>>
>> I wrote a function in C, which works fine if called from the
>> main-function in C.
>>
>> But as soon as I try to call this function from R like .C('foo',
>> as.double(x), as.integer(y)), the programm crashes.
>>
>> I created a dll with the cmd command R --arch x64 CMD SHLIB foo.c and
>> loaded it into R with dyn.load().
>>
>> What can be the cause of such behaviour?
>> Again, the C-funcion itself works, but not if called from R.
>>
>> Thanks
>> Grigory Alexandrovich
>>
>> ______________________________________________
>> R-help at r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-help
>> PLEASE do read the posting guide
>> http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.