Question

I want to convert IList to array:
Please see my code:

IList list = new ArrayList();
list.Add(1);
Array array = new Array[list.Count];
list.CopyTo(array, 0);

Why I get System.InvalidCastException : At least one element in the source array could not be cast down to the destination array type? How that can be resolved assuming I can not use ArrayList as type for list variable ?

Update 1: I use .NET 1.1. So I can not use Generics, Linq and so on. I just want to receive result for the most common case – integer was given as example, I need this code works for all types so I use Array here (maybe I am wrong about using Array but I need, once again, common case).

Answer 1

You’re creating an array of Array values. 1 is an int, not an Array. You should have:

IList list = new ArrayList();
list.Add(1);
Array array = new int[list.Count];
list.CopyTo(array, 0);

or, ideally, don’t use the non-generic types to start with… use List instead of ArrayList, IList<T> instead of IList etc.

EDIT: Note that the third line could easily be:

Array array = new object[list.Count];

instead.