using System;

using System.Globalization;

public class Program

{

    public static void Main()

    {

        var s = "1,5";

        DateTime d;

​

        var b = DateTime.TryParse(s, CultureInfo.InvariantCulture, DateTimeStyles.None, out d);

​

        Console.WriteLine("s: " + s);

        Console.WriteLine("b: " + b);

        Console.WriteLine("d: " + d);

    }

}