using System;

using System.Text.RegularExpressions;

​

public class Program

{

    public static void Main()

    {

        string source = "0.";

        if (Regex.IsMatch(source,  @"^\-?[0-9]+(?:\.[0-9]{1,2})?$")) {

            Console.WriteLine("MATCH");

          } 

        else { Console.WriteLine("NOT MATCH"); }

        Console.WriteLine(System.Text.RegularExpressions.Regex.Replace("1D.3", "[^.0-9]", ""));

        Console.WriteLine(Math.Truncate(1.2));

​

    }

}