How to Change System Date Programatically

Question

How can I Change Local System DateTime Programatically with C# ?

Answer 1

1. PInvoke to call Win32 API SetSystemTime,(example)
2. System.Management classes with WMI class Win32_OperatingSystem and call SetDateTime on that class.

Both require that the caller has been granted SeSystemTimePrivilege and that this privilege is enabled.

Answer 2

One of the many links found when you google "c# change system date".

Answer 3

Here is where I found the answer.

I have reposted it here to improve clarity.

Define this structure:

[StructLayout(LayoutKind.Sequential)]
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;
}

Add the following extern method to your class:

[DllImport("kernel32.dll", SetLastError = true)]
public static extern bool SetSystemTime(ref SYSTEMTIME st);

Then call the method with an instance of your struct like this:

SYSTEMTIME st = new SYSTEMTIME();
st.wYear = 2009; // must be short
st.wMonth = 1;
st.wDay = 1;
st.wHour = 0;
st.wMinute = 0;
st.wSecond = 0;

SetSystemTime(ref st); // invoke this method.

Answer 4

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);
}

Answer 5

Since I mentioned it in a comment, here's a C++/CLI wrapper:

#include <windows.h>
namespace JDanielSmith
{
    public ref class Utilities abstract sealed /* abstract sealed = static */
    {
    public:
     CA_SUPPRESS_MESSAGE("Microsoft.Security", "CA2122:DoNotIndirectlyExposeMethodsWithLinkDemands")
     static void SetSystemTime(System::DateTime dateTime) {
      LARGE_INTEGER largeInteger;
      largeInteger.QuadPart = dateTime.ToFileTimeUtc(); // "If your compiler has built-in support for 64-bit integers, use the QuadPart member to store the 64-bit integer."


      FILETIME fileTime; // "...copy the LowPart and HighPart members [of LARGE_INTEGER] into the FILETIME structure."
      fileTime.dwHighDateTime = largeInteger.HighPart;
      fileTime.dwLowDateTime = largeInteger.LowPart;


      SYSTEMTIME systemTime;
      if (FileTimeToSystemTime(&fileTime, &systemTime))
      {
       if (::SetSystemTime(&systemTime))
        return;
      }


      HRESULT hr = HRESULT_FROM_WIN32(GetLastError());
      throw System::Runtime::InteropServices::Marshal::GetExceptionForHR(hr);
     }
    };
}

The C# client code is now very simple:

JDanielSmith.Utilities.SetSystemTime(DateTime.Now);