C# Cast Entire Array?

Question

I see this Array.ConvertAll method, but it requires a Converter as an argument. I don't see why I need a converter, when I've already defined an implicit one in my class:

    public static implicit operator Vec2(PointF p)
    {
        return new Vec2(p.X, p.Y);
    }

I'm trying to cast an array of PointFs to an array of Vec2s. Is there a nice way to do this? Or should I just suck it up and write (another) converter or loop over the elements?

Answer 1

Cast doesn't consider user defined implicit conversions so you can't cast the array like that. You can use select instead:

myArray.Select(p => (Vec2)p).ToArray();

Or write a converter:

Array.ConvertAll(points, (p => (Vec2)p));

The latter is probably more efficient as the size of the result is known in advance.

Answer 2

The proposed LINQ solution using Cast/'Select' is fine, but since you know you are working with an array here, using ConvertAll is rather more efficienct, and just as simple.

var newArray = Array.ConvertAll(array, item => (NewType)item);

Using ConvertAll means a) the array is only iterated over once, not twice, b) the operation is more optimised for arrays (does not use IEnumerator<T>).

Don't let the Converter<TInput, TOutput> type confuse you - it is just a simple delegate, and thus you can pass a lambda expression for it, as shown above.