string в string array

https://ideone.com/mNsfqL

using System;
using System.Linq;
using System.Text.RegularExpressions;

public class Test
{
  public static void Main()
  {
    var s = "13+7-4/2+12";
    string[] tokens = Regex.Matches(s, @"\d+|[-+/*()]").Cast<Match>().Select(m => m.Value).ToArray();
    Console.WriteLine(string.Join("\n", tokens));
  }
}