using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Data;

using System.Drawing;

using System.Linq;

using System.Text;

using System.Windows.Forms;

using Microsoft.Win32;

using System.Runtime.InteropServices;

namespace WindowsFormsApplication1

{

    public partial class Form1 : Form

    {

        public Form1()

        {

            InitializeComponent();

        }

        //using System.Runtime.InteropServices;

        [StructLayout(LayoutKind.Sequential)]

        public struct SystemTime

        {

            public ushort wYear;

            public ushort wMonth;

            public ushort wDayOfWeek;

            public ushort wDay;

            public ushort wHour;

            public ushort wMinute;

            public ushort wSecond;

            public ushort wMiliseconds;

        }

        [DllImport("kernel32.dll")]

        public static extern bool SetLocalTime(

            ref SystemTime sysTime);

        /// <summary>

        /// 現在のシステム日時を設定する

        /// </summary>

        /// <param name="dt">設定する日時</param>

        public static bool SetNowDateTime(DateTime dt)

        {

            //システム日時に設定する日時を指定する

            SystemTime sysTime = new SystemTime();

            sysTime.wYear = (ushort)dt.Year;

            sysTime.wMonth = (ushort)dt.Month;

            sysTime.wDay = (ushort)dt.Day;

            sysTime.wHour = (ushort)dt.Hour;

            sysTime.wMinute = (ushort)dt.Minute;

            sysTime.wSecond = (ushort)dt.Second;

            sysTime.wMiliseconds = (ushort)dt.Millisecond;

            //システム日時を設定する

             return SetLocalTime(ref sysTime);

        }

        private void Form1_Load(object sender, EventArgs e)

        {

            timer1.Enabled = true;

        }

        private void button1_Click(object sender, EventArgs e)

        {

            label2.Text = SetNowDateTime(new DateTime(2005, 1, 2, 0, 0, 0)) ? "成功しました。" : "失敗しました。";

            textBox1.Text = DateTime.Now.ToString();

        }

        private void timer1_Tick(object sender, EventArgs e)

        {

            textBox1.Text = DateTime.Now.ToString();

        }

    }

}