using System;

using System.Globalization;

public class Program

{

    public static void Main()

    {

        string str = " 2012-03-20T14:18:25.000+04:00";

DateTimeOffset dto = DateTimeOffset.Parse(str);

//Get the date object from the string. 

DateTime dtObject = dto.DateTime; 

​

//Convert the DateTimeOffSet to string. 

string newVal = dto.ToString("o");

        Console.WriteLine (newVal);

            DateTime.ParseExact(newVal,'yyyy-MM-ddTHH:mm:ss.SSSZ',null);

            //DateTime.ParseExact(dtNow,format,null,System.Globalization.DateTimeStyles.None);

    //DateTime.ParseExact(dateComponent, "yyyy-MM-dd",null)

        Console.WriteLine (DateTime.Parse(newVal));

    }

    public static void ParseDate (string value, string[] masks, out DateTime result)

    {   

        DateTime.TryParseExact(value, masks,

            System.Globalization.CultureInfo.InvariantCulture,

            System.Globalization.DateTimeStyles.AssumeUniversal

            | System.Globalization.DateTimeStyles.AdjustToUniversal

            | System.Globalization.DateTimeStyles.AllowInnerWhite

            | System.Globalization.DateTimeStyles.AllowLeadingWhite

            | System.Globalization.DateTimeStyles.AllowTrailingWhite,

                out result);

    }

}