On 8/3/15 5:23 PM, ref2401 wrote:
Hello everyone,
I pass a D array as void* into a function.
When I'm trying to cast a void* parameter to a D array I get 'Access
Violation' error.
However if I define ArrayLike struct which looks like D array then
casting will succeed.
What should I do? Should I stick to ArrayLike wrapper and just live? :)
struct ArrayLike(T) {
this(T[] arr) {
ptr = arr.ptr;
length = arr.length;
}
T* ptr;
size_t length;
In T[], length is stored first, then pointer. This is likely where you
are getting hung up. You didn't post your C code, so I don't know
exactly what you are expecting on the other side.
T[] asArray() {
return ptr[0 .. length];
}
}
void funcLibC_Array(void* data) {
int[] arr = *cast(int[]*)data;
writeln("funcLibC_Array: ", arr);
}
void funcLibC_ArrayLike(void* data) {
ArrayLike!int arrLike = *cast(ArrayLike!int*)data;
writeln("funcLibC_ArrayLike: ", arrLike.asArray());
}
void main(string[] args) {
int[] arr = [1, 2, 3];
auto arrLike = ArrayLike!int(arr);
funcLibC_ArrayLike(&arrLike);
funcLibC_Array(arr.ptr); // 'Access Violation error' is thrown here.
This is wrong, arr.ptr is just the pointer to the DATA, not a pointer to
an array struct (which contains pointer and length). You want to do
funcLibC_Array(&arr);
Posting your C code (at least the part that reestablishes the type from
a void*) may give more clarity to what you are trying to do.
-Steve
