public static class Shutdown
{
    [StructLayout(LayoutKind.Sequential, Pack = 1)]
    internal struct TokPriv1Luid
    {
        public int Count;
        public long Luid;
        public int Attr;
    }
    [DllImport("kernel32.dll", ExactSpelling = true)]
    internal static extern IntPtr GetCurrentProcess();
    [DllImport("advapi32.dll", ExactSpelling = true, SetLastError = true)]
    internal static extern bool OpenProcessToken(IntPtr h, int acc, ref IntPtr phtok);
    [DllImport("advapi32.dll", SetLastError = true)]
    internal static extern bool LookupPrivilegeValue(string host, string name, ref long pluid);
    [DllImport("advapi32.dll", ExactSpelling = true, SetLastError = true)]
    internal static extern bool AdjustTokenPrivileges(IntPtr htok, bool disall,
    ref TokPriv1Luid newst, int len, IntPtr prev, IntPtr relen);

    [DllImport("user32.dll", ExactSpelling = true, SetLastError = true)]

    internal static extern bool ExitWindowsEx(int DoFlag, int rea);
    internal const int SE_PRIVILEGE_ENABLED = 0x00000002;
    internal const int TOKEN_QUERY = 0x00000008;
    internal const int TOKEN_ADJUST_PRIVILEGES = 0x00000020;
    internal const string SE_SHUTDOWN_NAME = "SeShutdownPrivilege";
    internal const int EWX_LOGOFF = 0x00000000;
    internal const int EWX_SHUTDOWN = 0x00000001;
    internal const int EWX_REBOOT = 0x00000002;
    internal const int EWX_FORCE = 0x00000004;
    internal const int EWX_POWEROFF = 0x00000008;
    internal const int EWX_FORCEIFHUNG = 0x00000010;


    private static void DoExitWin(int DoFlag)
    {
        bool ok;
        TokPriv1Luid tp;
        IntPtr hproc = GetCurrentProcess();
        IntPtr htok = IntPtr.Zero;
        ok = OpenProcessToken(hproc, TOKEN_ADJUST_PRIVILEGES | TOKEN_QUERY, ref htok);
        tp.Count = 1;
        tp.Luid = 0;
        tp.Attr = SE_PRIVILEGE_ENABLED;
        ok = LookupPrivilegeValue(null, SE_SHUTDOWN_NAME, ref tp.Luid);
        ok = AdjustTokenPrivileges(htok, false, ref tp, 0, IntPtr.Zero, IntPtr.Zero);
        ok = ExitWindowsEx(DoFlag, 0);
    }

    public static void Reboot()
    {
        DoExitWin(EWX_FORCE | EWX_REBOOT);
    }
    public static void PowerOff()
    {
        DoExitWin(EWX_FORCE | EWX_POWEROFF);
    }
    public static void LogOff()
    {
        DoExitWin(EWX_FORCE | EWX_LOGOFF);
    }
}