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How do I pass an array to an xsub?
Posted on 2001-07-03
I want to pass a Perl array as an argument to an xsub subroutine. The xsub will then pass it on to a C library function that expects int xyz[]. How do I code the xsub?
If you need a more concrete example, what I'm trying to do is make a Perl version of setgroups(), which is int setgroups(size_t size, const gid_t *list) in C.
I can't find any documentation other than overview of the xsub interface and typemap file.
If you need a more concrete example, what I'm trying to do is make a Perl version of setgroups(), which is int setgroups(size_t size, const gid_t *list) in C.
I can't find any documentation other than overview of the xsub interface and typemap file.
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------------------- xsub code ------------------
int
setgroups(...)
PREINIT:
int i;
gid_t *glist;
CODE:
if( items > 0 ) {
glist = (gid_t *)malloc(items * sizeof(gid_t));
for (i = 0; i < items; i++)
glist[i] = SvIV(ST(i));
RETVAL = setgroups( items, glist );
free (glist);
}
OUTPUT:
RETVAL
--------------------------
- Sapa
int
setgroups(...)
PREINIT:
int i;
gid_t *glist;
CODE:
if( items > 0 ) {
glist = (gid_t *)malloc(items * sizeof(gid_t));
for (i = 0; i < items; i++)
glist[i] = SvIV(ST(i));
RETVAL = setgroups( items, glist );
free (glist);
}
OUTPUT:
RETVAL
--------------------------
- Sapa
That's more of an example of a variable number of scalar arguments. That's good; I hadn't realized that's what I need for setgroups(), so thanks for that. But what if I have a single argument that is an array, for example
sub1($a, @b, $c);
Or is that even meaningful in Perl?
sub1($a, @b, $c);
Or is that even meaningful in Perl?
"sub1($a, @b, $c);"
In this call:
$a will be in ST(0)
$c will be in ST(items-1)
@b will be in ST(1)..ST(items-2)
because all arguments concatenated into one
list passed to called function.
except if you have defined function
prototype as
sub sub1($\@$)
in this case, there will be 3 arguments
passed scalar, _reference_ to array, and
one more scalar. But it's unnecessary in
your case.
- Sapa
In this call:
$a will be in ST(0)
$c will be in ST(items-1)
@b will be in ST(1)..ST(items-2)
because all arguments concatenated into one
list passed to called function.
except if you have defined function
prototype as
sub sub1($\@$)
in this case, there will be 3 arguments
passed scalar, _reference_ to array, and
one more scalar. But it's unnecessary in
your case.
- Sapa
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