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

Answer 1

As an update to this old question, you can now do:

myArray.Cast<Vec2>().ToArray();

where myArray contains the source objects, and Vec2 is the type you want to cast to.

Answer 2

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 3

The most efficient way is:

class A { };
class B : A { };

A[] a = new A[9];
B[] b = a as B[];

Answer 4

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,
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.