C#中如何更改当前时间

using System.Runtime.InteropServices;

//imports SetLocalTime function from kernel32.dll
[DllImport("kernel32.dll", SetLastError=true)]
public static extern int SetLocalTime (ref SystemTime lpSystemTime);

//struct for date/time apis
public struct SystemTime
{
public short wYear;
public short wMonth;
public short wDayOfWeek;
public short wDay;
public short wHour;
public short wMinute;
public short wSecond;
public short wMilliseconds;
}

// And then set up a structure with the required properties and call the api from code:

SystemTime systNew = new SystemTime();

// 设置属性
systNew.wDay = 1;
systNew.wMonth = 1;
systNew.wYear = 2004;
systNew.wHour = 9;
systNew.wMinute = 0;
systNew.wSecond = 0;

// 调用API，更新系统时间
SetLocalTime(ref systNew);

创建对象 DateTime dt = new DateTime();
dt实例中有好多方法都