Subset of Array in C#

Question

If I have an array with 12 elements and I want a new array with that drops the first and 12th elements. For example, if my array looks like this:

__ __ __ _         


        

Answer 1

C# 8 has a Range and Index type

char[] a = { 'a', 'b', 'c',  'd',  'e',  'f',  'g',  'h',  'i',  'j',  'k',  'l' };
Index i1 = 1;  // number 1 from beginning
Index i2 = ^1; // number 1 from end
var slice = a[i1..i2]; // { 'b','c','d','e','f','g','h','i','j' }

Answer 2

You can do this with Array.Copy or LINQ.

var letters = string[] { "a", "b", "c", "d", "e", "f", "g", "h", "i" };

int length = letters.Length - 2;
var items = new string[length];
Array.Copy(letters, 1, items, 0, length);
// or
var items = letters.Skip(1).Take(length).ToArray();

Answer 3

You can use ArraySegment<T> structure like below:

var arr = new[] { 1, 2, 3, 4, 5 };
var offset = 1;
var count = 2;
var subset = new ArraySegment<int>(arr, offset, count)
             .ToArray(); // output: { 2, 3 }

Check here for an extension method that makes use of it even easier.

Answer 4

LINQ is your friend. :)

var newArray = oldArray.Skip(1).Take(oldArray.Length - 2).ToArray();

Somewhat less efficient than manually creating the array and iterating over it of course, but far simple...

The slightly lengithier method that uses Array.Copy is the following.

var newArray = new int[oldArray.Count - 2];
Array.Copy(oldArray, 1, newArray, 0, newArray.Length);

Answer 5

Array.Copy() will do that for you, but you still have to create your new array with its correct size.

Answer 6

string[] s = initialize the array...

var subset = s.Skip(1).Take(s.Length - 2).ToArray();