## PRB: CFile::SetStatus Sets Archive Bit when Not Desired

Q117832

    7.00   | 1.00 1.50
    MS-DOS | WINDOWS
    kbprg kbprb

    ----------------------------------------------------------------------
    The information in this article applies to:

     - The Microsoft Foundation Classes (MFC), included with:

        - Microsoft C/C++ version 7.0
        - Microsoft Visual C++ for Windows, versions 1.0 and 1.5
    ----------------------------------------------------------------------

    SYMPTOMS
    ========

    Attempting to clear the archive bit of a file when the archive bit is
    already cleared causes the archive bit to be set.

    CAUSE
    =====

    This is expected behavior that results when the m_mtime member of the
    CFileStatus structure is not set to 0, indicating that the time should be
    updated. Because updating the time has the side effect of setting the
    archive bit for a file, this action takes precedence over clearing the
    archive bit when the bit was clear to begin with.

    RESOLUTION
    ==========

    1. If you want to clear only the archive bit, set the m_mtime member
       to 0, which indicates that you do not want to change the file time:

          CFile::GetStatus("TEMP.DAT",fs);
          fs.m_mtime=0;
          fs.m_attribute = fs.m_attribute & !CFile::archive;
          CFile::SetStatus("TEMP.DAT",fs);

    2. Check to see whether the archive bit is clear instead of making a
       redundant call to clear it:

          CFile::GetStatus("TEMP.DAT",fs);
          if(fs.m_attribute & CFile::archive)
          {
            fs.m_attribute = fs.m_attribute & !CFile::archive;
            CFile::SetStatus("TEMP.DAT",fs);
          }

    MORE INFORMATION
    ================

    To duplicate this behavior, create a test file called TEMP.DAT and run
    the sample code below:

    Sample Code
    -----------

    // Using the MS-DOS ATTRIB command, watch the archive bit toggle
    // after each time you run the program.

       #define _DOS
       #include <afx.h>

       CFileStatus fs;

       void main(void) {
         CFile::GetStatus("TEMP.DAT",fs);
         fs.m_attribute = fs.m_attribute & !CFile::archive;
         CFile::SetStatus("TEMP.DAT",fs);
       }

    This behavior does not occur with Visual C++ 32-bit Edition.

    REFERENCES
    ==========

    The possible side effects of m_mtime on file attributes are discussed in
    the "Class Library Reference" for Visual C++, version 1.5, page 411.

    Additional reference words: 7.00 1.00 1.50 2.00 2.50
    KBCategory: kbprg kbprb
    KBSubcategory: MfcFileIO

Keywords : kb16bitonly
Issue type :
Technology : kbAudDeveloper kbMFC

Last Reviewed: May 5, 2001 © 2001 Microsoft Corporation. All rights reserved. Terms of Use.