Why doesn't Array class expose its indexer directly?

Question

something to mention for answering:

1. Don\'t worry about variance, while the item in question is Array rather than

Answer 1

Short answer:

System.Array is a base class for N-D arrays (not only 1-D), that's why 1-D indexer (object this[i]{get;set;}) cannot be a base member.

Long answer:

If you let's say create 2-dimensional array and try to access it's IList indexer:

Array a;
a=Array.CreateInstance(typeof(char), 1,1);
(a as IList)[0]='a';

You will get not supported exception.

Good question would be:

Why System.Array implement IList and IEnumerable while most of its implementation will throw NotSupportedException for non 1-D array??

One more interesting thing to mention. Technically non of the arrays have class-indexer internally in classic meaning. Classic meaning of Indexer is a property "Item" + get(+set) method(s). If you go deep to reflection you will see that typeof(string[]) does not have indexer property and it only has 2 methods Get and Set - those method declared in string[] class (not in base class, unlike Array.SetValue, Array.GetValue) and they are used for compile-time indexing.