How Does Cardfile Verify Writes? (82823)


The information in this article applies to:

  • Microsoft Windows 3.1
  • Microsoft Windows 3.11
This article was previously published under Q82823

SUMMARY

In Microsoft Windows version 3.1, the Cardfile accessory application has a Validate Writes check box in the File Save dialog box. If this check box is selected, then Cardfile verifies the integrity of the changes it writes to the file.

MORE INFORMATION

When Save or Save As is chosen from the File menu, Cardfile writes the changes to a temporary file. If Validate Writes is selected, Cardfile then reopens this temporary file and checks that it can read it.

Cardfile does not compare the files card by card, but merely makes certain that the file opened is in a valid Cardfile format by checking the validity of the following:

  • The header for the whole file
  • The header for each card
If one of the above checks fails, the temporary file is not considered valid. This means that if only one card is corrupted, the whole file will be marked as bad.

If the temporary file is valid, the temporary file is renamed to the filename you specify. By performing the validation in this manner, the old file is not corrupted when you try to update it with more information.

Cardfile for Windows 3.1 has a new format that allows it to support OLE and contain pictures. The new format entails a change in the header for the file. If the file contains a picture, Cardfile saves the file in this new format. If it does not contain a picture, Cardfile saves the file in the format used in Cardfile for Windows version 3.0, allowing both versions to read it. If someone takes a file containing a picture and tries to open it using the 3.0 version of Cardfile, the following message will appear:
Not A Valid Cardfile
For more information on the Cardfile format, query on the following words in the Microsoft Knowledge Base:

appnote and cardfile and format
validateFileWrite=1

Modification Type:MajorLast Reviewed:10/13/2003
Keywords:KB82823
©2003 Microsoft Corporation. All rights reserved.