Coordinated Universal Time on MS-DOS vs. Windows NT

WINDOWS             | WINDOWS NT

The information in this article applies to:

• The Microsoft Foundation Classes (MFC) included with:

      - Microsoft Visual C++ for Windows, versions 1.0, 1.5, 1.51, and
        1.52
      - Microsoft Visual C++ 32-bit Edition, versions 1.0, 2.0, 2.1, and 4.0
  

If a data file containing MFC CTime objects is moved from MS-DOS (including Windows) to Windows NT, or vice-versa, differences in the system time under MS-DOS and Windows NT can cause unexpected results.

Under MS-DOS, Pacific Standard Time is the default time zone. The default time zone for Windows NT is Greenwich Mean Time. MFC CTime objects use Coordinated Universal Time (UTC) to store the current time. This can cause problems if CTime objects are shared between applications on default installations of MS-DOS (Windows) and Windows NT. Specifically, the time will be 8 hours off.

This is expected behavior for any object that uses UTC. To share data files, make sure that both systems use the same time zone. If you want to use an absolute time (one that remains the same regardless of time zone), you must implement your own object.