DOCUMENT:Q258998  11-APR-2000  [foxpro]
TITLE   :PRB: DateTime Subtraction May Not Produce an Exact Integer
PRODUCT :Microsoft FoxPro
PROD/VER:WINDOWS:5.0,5.0a,6.0
OPER/SYS:
KEYWORDS:kbvfp500 kbvfp500a kbvfp600 kbXBase kbGrpDSFox kbDSupport

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

 - Microsoft Visual FoxPro for Windows, versions 5.0, 5.0a, 6.0 
-------------------------------------------------------------------------------

SYMPTOMS
========

When subtracting two DateTimes, the result is a floating point number. As such,
the displayed value may not be the exact value. This may lead to further
inaccuracies.

CAUSE
=====

Floating point math is frequently inaccurate in any language.

RESOLUTION
==========

When subtracting DateTimes, use ROUND(nDifference, 0) to ensure that you are
working with the value you think you are.

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

Steps to Reproduce Behavior
---------------------------

To observe the problem, run the following code in the Command window:

   lnDiff = {^2000-03-20 11:31:00} - {^2000-03-20 10:25:00}
   ? lnDiff                      && 3960
   DISPLAY MEMORY LIKE lnDiff    && 3959.99996513
   ? INT(lnDiff)                 && 3960
   ? INT(lnDiff / 60)            && 65
   ? INT(ROUND(lnDiff, 0) / 60)  && 66

Additional query words:

======================================================================
Keywords          : kbvfp500 kbvfp500a kbvfp600 kbXBase kbGrpDSFox kbDSupport 
Technology        : kbVFPsearch kbAudDeveloper kbVFP500 kbVFP600 kbVFP500a
Version           : WINDOWS:5.0,5.0a,6.0
Issue type        : kbprb
Solution Type     : kbnofix

=============================================================================

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS
PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND.  MICROSOFT DISCLAIMS
ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES
OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.  IN NO
EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR
ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL,
CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF
MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE
POSSIBILITY OF SUCH DAMAGES.  SOME STATES DO NOT ALLOW THE EXCLUSION
OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES
SO THE FOREGOING LIMITATION MAY NOT APPLY.

Copyright Microsoft Corporation 2000.