bbcannon [10/06/02 09:30 -0600]:
> I am receiving a "parse" error when I try to declare an array of doubles.
> However, I don't see a problem with my syntax.
>
> Is something special required to create arrays with Inline ?
The short answer:
Your syntax is valid Perl, almost valid C++, but not valid C. To create
(static) arrays within C, you must know the size of the array at
compile time.
The long answer:
Let me paraphrase the important section of your code:
void
some_function(SV *x) {
AV *arr;
int maxIndex;
int numElements;
arr = SvRV(x);
maxIndex = av_len(arr);
numElements = maxIndex + 1;
double data[numElements];
}
That's not legal C for two reasons:
1. You can only declare new variables at the beginning of a new scope,
before the first non-declaration.
/* This is legal: */
{
int hello;
printf("foo!\n");
}
/* This is not */
{
printf("foo!\n");
int hello;
}
Move the "double data" declaration up to the top of the scope, above
the first non-declaration statement. That leads us to...
2. You can only declare fixed-size static arrays if the size is known at
compile-time. In your case, where the size depends on the length of the
AV*, you will have to use New() or Newz() to allocate a temporary array
yourself:
{
int maxIndex, numElements;
AV *arr;
double *data;
...
Newz(0, data, numElements, double);
SAVEFREEPV(data); /* Safefree() 'data' on scope exit */
...
}
Notice the SAVEFREEPV(), which automatically calls Safefree() for you when
you leave the Perl XSUB, no matter how you leave it. Pretty neat, IMHO.
Hope that helps!
Later,
Neil
