Initial data commit

Task/Middle-three-digits/Elixir/middle-three-digits.elixir

@@ -0,0 +1,30 @@
+defmodule Middle do
+  def three(num) do
+    n = num |> abs |> to_string
+
+    case {n,String.length(n) > 2,even?(n)} do
+      {n, true, false} ->
+        cut(n)
+      {_, false, _} ->
+        raise "Number must have at least three digits"
+      {_, _, true} ->
+        raise "Number must have an odd number of digits"
+    end
+  end
+
+  defp even?(n), do: rem(String.length(n),2) == 0
+  defp cut(n), do: String.slice(n,(div(String.length(n),2) - 1),3)
+end
+
+valids = [123, 12345, 1234567, 987654321, 10001, -10001, -123, -100, 100, -12345]
+Enum.each(valids, fn n -> :io.format "~10w : ~s~n", [n, Middle.three(n)] end)
+
+errors = [1, 2, -1, -10, 2002, -2002, 0]
+Enum.each(errors, fn n ->
+  :io.format "~10w : ", [n]
+  try do
+    IO.puts Middle.three(n)
+  rescue
+    e -> IO.puts e.message
+  end
+end)