Array slices in C#

You could use ArraySegment<T>. It's very light-weight as it doesn't copy the array:

string[] a = { "one", "two", "three", "four", "five" };
var segment = new ArraySegment<string>( a, 1, 2 );

Arrays are enumerable, so your foo already is an IEnumerable<byte> itself. Simply use LINQ sequence methods like Take() to get what you want out of it (don't forget to include the Linq namespace with using System.Linq;):

byte[] foo = new byte[4096];

var bar = foo.Take(41);

If you really need an array from any IEnumerable<byte> value, you could use the ToArray() method for that. That does not seem to be the case here.

You could use the arrays CopyTo() method.

Or with LINQ you can use Skip() and Take()...

byte[] arr = {1, 2, 3, 4, 5, 6, 7, 8};
var subset = arr.Skip(2).Take(2);