[CExt] C array to Ruby Array?

thomthom

Say you have a C array, int carr[10]; or double carr[10];.
Is there a single method to convert the C array to a Ruby array?

Or does one have to create a Ruby array, iterate the C array and populate one value at a time?

MartinRinehart

Ruby has its wonderful numbers (integers when possible, floats as needed) but they aren't C's much simpler (and faster) plain numbers. Cs numbers can be used directly by the CPU/FPU. Ruby's numbers are object instances.

thomthom

I am writing a Ruby C Extension. What I tried to hint by [CExt].

TDB let me know I need to do the latter in order to convert C arrays to Ruby arrays.

AdamB

Generally No, because the underlying representations are different. (eg Integer in Ruby is actually an integer times 4)

Doubles are the exception as the representation in C and Ruby are the same IEEE format.

So the values can simply be copied. However the container is another matter; in C, arrays are little more than syntactic sugar, in Ruby an Array is a real live object, so you're kinda out luck.

The best you could do would be something like:


extern double *reals
extern int rcount;

static VALUE
method_getRealArray(VALUE rarray)
{
  if (rcount < RARRAY_LEN(rarray))
  {
    memcpy(RARRAY_PTR(rarray), reals, sizeof(double)* rcount);  
    return Qtrue;
 }
  else
  {
    return Qfalse;
  } 
}