Node.js C++ Addon - Setting a certain index of an array

Question

I'm trying to create a Node.js C++ Addon that generates the Fibonacci sequence to compare its speed with a normal Node.js module, but I'm having trouble setting a certain index of an array. I've got this so far:

#include <node.h>

namespace demo {

using v8::FunctionCallbackInfo;
using v8::Isolate;
using v8::Local;
using v8::Object;
using v8::Value;
using v8::Number;
using v8::Array;

void Method(const FunctionCallbackInfo<Value>& args) {
    Isolate* isolate = args.GetIsolate();

    int next, first = 0, second = 0, c = 0, n = args[0]->NumberValue();
    Local<Array> arr = Array::New(isolate, n);

    for (; c < n; c++) {
        if ( c <= 1 ) next = c;
        else {
            next = first + second;
            first = second;
            second = next;
        }
        // How to set arr[c]?????
    }

    args.GetReturnValue().Set(arr);
}

void init(Local<Object> exports) {
    NODE_SET_METHOD(exports, "fib", Method);
}

NODE_MODULE(addon, init)

}

On line 26, how should I set arr[c]? v8:Array doesn't provide a subscript operator.

Answer 1

how should I set arr[c]? v8:Array doesn't provide a subscript operator.

It doesn't, but v8::Array already inherits the function member Set from v8::Object, with an overload that takes an integer (uint32_t) for the key. Use it to populate each element of the array:

void Method(const FunctionCallbackInfo<Value>& args) {
    Isolate* isolate = args.GetIsolate();

    int next, first = 0, second = 0, c = 0, n = args[0]->NumberValue();
    Local<Array> arr = Array::New(isolate, n);

    int i = 0;
    for (; c < n; c++) {
        if ( c <= 1 ) next = c;
        else {
            next = first + second;
            first = second;
            second = next;
        }
        arr->Set(i++, Number::New(isolate, next));
    }

    args.GetReturnValue().Set(arr);
}