get bytes from array function vb.net

Question

I need to get the bytes from an array of bytes starting at a certain index and for a certain length (4), how can get this?

Note: I don't want to use the Array.copy sub as it is not a function. I need to put it in something like Sub MySub([arguement as byte()]the_function_I_Need(Array, index, length))

Answer 1

Something like:

Dim portion As Byte() = New Byte(length - 1) {}
Array.Copy(originalArray, index, portion, 0, length)

The "- 1" is because of VB taking the last element index rather than the size.

EDIT: I missed the bit about not wanting to use Array.Copy. (Was it there when I posted the answer, or did you edit it in within the five minutes "grace period"?)

Just wrap this into a method if you really need to. While there are alternatives using LINQ etc, this will be the most efficient way of doing it if you genuinely want a new array.

There's also ArraySegment(Of T) if you're happy to use a wrapper around the existing array - but that's not the same thing.

Answer 2

Private Function the_function_you_need(ByVal arr As Byte(), ByVal ix As Integer, _
    ByVal len As Integer) As Byte()

    Dim arr2 As Byte() = New Byte(len - 1)
    Array.Copy(arr, ix, arr2, 0, len)
    Return arr2

End Function