Create dynamic array of Entry

Question

I need to create an array from data I get form my API. The data needs to be in the object Entry which I get from the MicroCharts Library.

error is: Index was outside the bounds of the array. on the 2nd line.

the most this is one of my tries:

        var entries = new[]{ new Entry(2) { } };
        entries[2]=( new Entry(3) { });

        for (int i = 0; i < _CoinHistory.Count(); i++)
        {
            var price_float = float.Parse(_CoinHistory[0].price_btc);
            entries[i] = new Entry(price_float) { };
        }

the hardcoded part that works is this:

        var entries = new[]
        {
            new Entry(200)
            {
            },
            new Entry(400)
            {
            },
            new Entry(-100)
            {
            }
        };

edit:Both the answer from zaitsman as the answer from PiotrWolkowski work. just like the linq way.

Answer 1

Why not use Linq?

var entries = _CoinHistory.Select(x => new Entry(x.price_btc)).ToArray()

Answer 2

The error means you have exceeded the size of the array.

In C# once array is created it maintains it's size. You determine the size either by initializing the array with required amount of items, like in your example below:

    var entries = new[]
    {
        new Entry(200)
        {
        },
        new Entry(400)
        {
        },
        new Entry(-100)
        {
        }
    };

Or by providing the number of arguments as a parameter

var entries = new Entry[3]

Both will create an array of the size of 3, but the second one will be empty.

In your code in the first line you created an array of size 1 and then tried to assign a value to the third place in the array - which didn't exist.

If you want a dynamically resized collection use a List<Entry> instead and then, once your processing is completed turn it into an array with ToArray() call.

You can also initialize an array of the size of your results:

var entries = new Entry[_CoinHistory.Count()]