regarding Date time...............................

using System;

class Program
{
    static void Main()
    {
    DateTime d = new DateTime(2010, 1, 1);
    TimeZone cur = TimeZone.CurrentTimeZone;
    bool flag = !cur.IsDaylightSavingTime(d);

    for (int i = 0; i < 365; i++)
    {
        bool f = cur.IsDaylightSavingTime(d);
        if (f != flag)
        {
        Console.WriteLine("{0}: begin {1}", d, f);
        flag = f;
        }
        d = d.AddDays(1);
    }
    }
}