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Q189866: BUG: Incorrect Results When Comparing Large Numbers

Article: Q189866
Product(s): Microsoft FoxPro
Version(s): WINDOWS:5.0,5.0a,6.0
Operating System(s): 
Keyword(s): 
Last Modified: 11-DEC-1999

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The information in this article applies to:

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

When you compare two numbers for equality, you might receive an erroneous result
when the resulting numbers are very large.

NOTE: This behavior does not occur in Visual FoxPro 3.0x.

RESOLUTION
==========

Use the ROUND() function when checking the equality of very large floating-
point numbers. For example, the following line of code produces the correct
result:

     ?ROUND(1+(1048575+(i/1000)),5)=1048576.001

STATUS
======

Microsoft has confirmed this to be a bug in the Microsoft products listed at the
beginning of this article. We are researching this bug and will post new
information here in the Microsoft Knowledge Base as it becomes available.

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

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

Type the following commands in the Command window:

     SET DECIMAL to 5
     i=1
     ?(1+(1048575+(i/1000)))=1048576.001
     ?1+(1048575+(1/1000))=1048576.001

Notice that the first calculation, using the variable i, evaluates as false while
the calculation using the integer evaluates true.

Additional query words: kbVFp500bug kbVFp500abug kbVFp600bug kbXBase

======================================================================
Keywords          :  
Technology        : kbVFPsearch kbAudDeveloper kbVFP500 kbVFP600 kbVFP500a
Version           : WINDOWS:5.0,5.0a,6.0
Issue type        : kbbug
Solution Type     : kbnofix

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