using System;

public class Program

{

    public static void Main()

    { 

        var val1 = "5,7";

        var val2 = "5,7";

        if (Double.Parse(val1.ToString().Replace(",", ".")) !=

        Double.Parse(val2.ToString().Replace(",", ".")))

                        {

                            Console.WriteLine(

                                Double.Parse(val1.ToString()) + " is NOT " +

                                Double.Parse(val2.ToString())

                            );

                        }

    }

}

​

​