using System;

using System.Globalization;

public class Program

{

    private static CultureInfo usCulture = CultureInfo.CreateSpecificCulture("en-US");

    private static CultureInfo gbCulture = CultureInfo.CreateSpecificCulture("en-GB");

    private static CultureInfo invariantCulture = CultureInfo.InvariantCulture;

    public static string[] dateFormats = {"MM/dd/yyyy","dd/MM/yyyy","MM-dd-yyyy","dd-MM-yyyy","MM.dd.yyyy","dd.MM.yyyy","dd-MMM-yy"};

    public static void Main()

    {

        string DateFormat1 = "15/11/2019";

        string DateFormat2 = "11/15/2019";

        string DateFormat3 = "15-11-2019";

        string DateFormat4 = "11-15-2019";

        string DateFormat5 = "15.11.2019";

        string DateFormat6 = "11.15.2019";

        string DateFormat7 = "15-Nov-19";

        string[] DateFormats = new[] { DateFormat1, DateFormat2, DateFormat3, DateFormat4, DateFormat5, DateFormat6, DateFormat7 };

        foreach (string DateFormat in DateFormats)

            Console.WriteLine(DateStringToDate(DateFormat));

    }

​

    public static DateTime DateStringToDate(string dateValue)

    {

        DateTime formattedDate = DateTime.MinValue;

        foreach (string DateFormat in dateFormats){

            try{

                formattedDate = DateTime.ParseExact(dateValue,DateFormat, invariantCulture);

                continue;

            }

            catch(Exception){   

            }

        }

        return formattedDate;

        //if (dateValue.Contains("-"))

        //{

        //    try

        //    {

        //        formattedDate = DateTime.Parse(dateValue, invariantCulture).Date;

        //    }

        //    catch (Exception ex)

        //    {

        //        formattedDate = DateTime.ParseExact(dateValue, "dd-MM-yyyy", invariantCulture).Date;

        //    }

        //}

        //else

        //     try

        //    {

        //        formattedDate = DateTime.Parse(dateValue, usCulture).Date;

        //    }

        //    catch (Exception ex)

        //    {

        //        formattedDate = DateTime.ParseExact(dateValue, "dd/MM/yyyy", usCulture).Date;

        //    }

        //return formattedDate;

    }

}