using System;

using System.Collections;

using System.Collections.Generic;

using System.Text.RegularExpressions;

using org.mariuszgromada.math.mxparser;

​

public class Token

{

   public readonly string Name;

   public readonly string Value;

   public Token(string name, string value)

   {

      Name = name;

      Value = value;

   }

}

public class Program

{

    public static void Main()

    {

var pattern =

    @"(?<whitespace>\s*)|" +

    @"(?<variable>[a-zA-Z_$][a-zA-Z0-9_$]*)|" +

    @"(?<integer>[0-9]+)|" +

    @"(?<plus>\+)|" +

    @"(?<minus>-)|" +

    @"(?<multiply>\*)|" +

    @"(?<invalid>[^\s]+)";

    Regex regexPattern = new Regex(pattern);

    MatchCollection matches = regexPattern.Matches("365 + 6 * Count");      

var tokenList = new List<Token>();

foreach (Match match in matches)

{

   int i = 0;

   foreach (Group group in match.Groups)

   {

      string matchValue = group.Value;

      bool success = group.Success;

      // ignore capture index 0 and 1 (general and WhiteSpace)

      if ( success && i > 1)

      {

         string groupName = regexPattern.GroupNameFromNumber(i);

         tokenList.Add(new Token(groupName , matchValue));

      }

      i++;

   }

}

        foreach(var t in tokenList) {

            Console.WriteLine(t.Value);

        }

    }

}