Getting data array as iterable from C/C++ using ffi?

[kakyoism]

The official flutter tutorial on C/C++ interop through ffi only touches on calling a C++ function and getting a single return value.

Goal

What if I have a data buffer created on C/C++ side, but want to deliver to dart/flutter-side to show using the natural iteration syntax?

Problem

I'm testing Dart's FFI by trying to have safe memory deallocation from Dart to C/C++. The test reuses the official struct sample .

I could get the Array as a dart Pointer, but it's unclear to me how to iterate the array as a collection easily.

Code

I'm implementing a Dart-side C array binding like this:

In struct.h

struct Array
{
	int* array;
	int len;
};

and a pair of simple allocation/deallocation test functions:

struct Array* get_array();
int del_array(struct Array* arr);

Then on Dart side in structs.dart:

typedef get_array_func = Pointer<Array> Function();
typedef del_array_func = void Function(int arrAddress);

...

  final getArrayPointer = dylib.lookup<NativeFunction<get_array_func>>('get_array');
  final getArray = getArrayPointer.asFunction<get_array_func>();
  final arrayPointer = getArray();
  final array = arrayPointer.ref.array;
  print('array.array: $array');

This gives me the print out

array.array: Pointer<Int32>: address=0x7fb0a5900000

Question

Can I convert the array pointer to a List easily? Something like:

final array = arrayPointer.ref.array.toList();
array.forEach(idx, elem) => print("array[$idx]: $elem");

[kakyoism]

So asTypedList() is the answer

  final arrReal = array.asTypedList(10);
  arrReal.forEach((idx, elem) => print("array[$idx]: $elem"));