Re: [Swig-user] Interfacing C library for Perl using SWIG: Novice question

[Sandeep K. <san...@gm...>]

Hi,

You must have figured out how to get the values from an array.

I used this to retrieve the values from a C array.

sub get_array{
 $len =3D $_[0];
 $ia =3D $_[1];
 @arr[$len];
 for($i =3D 0;$i < $len;$i++){
   $arr[$i] =3D example::int_get($ia,$i);
 }
 return @arr;
}

Nothing needs to be added in the swig interface file.
int_get is already provided as you have mentioned.

Thanks
Sandeep


On 4/24/06, Albert Vernon Smith <av...@gm...> wrote:
>
> Hi Sandeep--
>
> I am trying to do the same as you, and have figured out how to pass
> arrays from Perl to C, but still need to figure out the reverse.  For
> starters, I have largely been following the page <http://www.swig.org/
> papers/Perl98/swigperl.htm> to get to this point.  It covers an older
> version of SWIG, though still has been very informative and helpful.
>
> First, I want to call the following test function:
>
> int func10(int mat[], int *len){
>         register int i;
>         int tmp;
>         tmp =3D *len;
>
>         for(i=3D0; i < tmp; i++)
>         {
>                 printf("%5.2d\n", mat[i]);
>         }
>         return;
> }
>
> I have defined the following typemap and helper functions in my
> interface file:
>
> %include typemaps.i
>
> %apply int *INPUT { int *len };
>
> %inline %{
> int *int_array(int size) {
>    return (int *) malloc(sizeof(int)*(4+size));
> }
> void int_destroy(int *a) {
>    free(a);
> }
> void int_set(int *a, int i, int val) {
>    a[i] =3D val;
> }
> int int_get(int *a, int i) {
>    return a[i];
> }
> %}
>
> Then, in perl, I have the following:
>
> sub create_array {
> my $len =3D scalar(@_);
> my $ia =3D example::int_array($len);
> for (my $i =3D 0; $i < $len; $i++) {
>     my $val =3D shift;
>     example::int_set($ia,$i,$val);
> }
> return $ia;
> }
>
> And I call everything as:
>
> my @a =3D (1..12);
> my $ia =3D create_array(@a);
> example::func10($ia, scalar(@a));
>
> This has worked fine for me.  (In reality, one also will need to
> destroy the arrays after one is done, and see the document I cited
> above on how to do that.)  You can use the same to also call is a
> function written as:
>
> int func11(int *mat, int *len)
>         {
>         register int i;
>                 int tmp;
>                 tmp =3D *len;
>
>         for(i =3D 0 ; i < tmp ; i++)
>                 {
>                         printf("%5.2d\n", *(mat + i));
>                 }
>         printf("\n");
>         return;
> }
>
> I think this should help solve part of what you want to do, but not
> how to get the results back to Perl, which I am also trying to figure
> out.  I'd certainly appreciate any insight anyone can give on that
> point.
>
> -albert
>
> On 24.4.2006, at 14:43, Sandeep Kumar wrote:
>
> > Hi,
> >
> > I have a library written in C and am trying to make a SWIG
> > interface to make it accessible in perl.
> > Am able to work with simple datatypes and structures.
> > But got stuck with arrays with types int*, char* and void * which
> > are being passed as arguments, returned as function values and are
> > present as member of struct.
> >
> > What I need is some direction, indicating which section of the SWIG
> > documentation I should look at for solution of this.
> > And if any examples available for this, that would be great.
> >
> > Thanks
> > Sandeep Kumar
>
>