using System;

public class Program

{

    public static void Main()

    {

        string dateTimeIn = DateTime.Now.ToString("MM/dd/yyyy HH:mm:ss.fff");

        string dateString = FormatDateTime(dateTimeIn, "yyyyMMddHHmmssfff");    

        Console.WriteLine(dateString);

        string dateString2 = DateTime.Now.ToString("yyyyMMddHHmmssfff");

        Console.WriteLine(dateString2);

        string dateString3 = FormatDateTime3(DateTime.Now, "yyyyMMddHHmmssfff");

        Console.WriteLine(dateString3);

    }

    public static string FormatDateTime(string dateValue, string format)

    {

        return DateTime.Parse(dateValue).ToString(format);

    }

    public static string FormatDateTime3(DateTime aDateValue, string format)

    {

        return aDateValue.ToString(format);

    }

}