Change system date programmatically

Question

How can I change the local system's date & time programmatically with C#?

Answer 1

You can use a call to a DOS command but the invoke of the function in the windows dll is a better way to do it.

public struct SystemTime
{
    public ushort Year;
    public ushort Month;
    public ushort DayOfWeek;
    public ushort Day;
    public ushort Hour;
    public ushort Minute;
    public ushort Second;
    public ushort Millisecond;
};

[DllImport("kernel32.dll", EntryPoint = "GetSystemTime", SetLastError = true)]
public extern static void Win32GetSystemTime(ref SystemTime sysTime);

[DllImport("kernel32.dll", EntryPoint = "SetSystemTime", SetLastError = true)]
public extern static bool Win32SetSystemTime(ref SystemTime sysTime);

private void button1_Click(object sender, EventArgs e)
{
    // Set system date and time
    SystemTime updatedTime = new SystemTime();
    updatedTime.Year = (ushort)2009;
    updatedTime.Month = (ushort)3;
    updatedTime.Day = (ushort)16;
    updatedTime.Hour = (ushort)10;
    updatedTime.Minute = (ushort)0;
    updatedTime.Second = (ushort)0;
    // Call the unmanaged function that sets the new date and time instantly
    Win32SetSystemTime(ref updatedTime);
}