来自:http://hi.baidu.com/ysdonet/blog/item/88fe5e0250ecbd0a4bfb5133.html
在C#里面，时间相关的对象都在DataTime 命名空间下，不过发现一般都是只能获取系统时间的，无法对系统时间进行修改，从网上查了很长时间资料才从http://www.csharphelp.com/找到解决方法，它是利用API来实现对系统时间的修改。
该API在C#是这样声名的:
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);
在通用的.net framework使用上面的方法就可以修改系统时间了，不过如果和我一样在.net compact framework环境下编程WinCE API都放在coredll.dll里面，而不是kernel32.dll、gdi32.dll、user32.dll里面，所以应该在API声明中修改一下动态库名
