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Q158756: BUG: Double Data Type Does Not Display Small Values Correctly

Article: Q158756
Product(s): Microsoft FoxPro
Version(s): WINDOWS:3.0,3.0b,5.0,5.0a,6.0
Operating System(s): 
Keyword(s): kbvfp kbvfp300bBUG kbvfp500aBUG kbvfp500bugkbbuglist
Last Modified: 11-DEC-1999

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The information in this article applies to:

- Microsoft Visual FoxPro for Windows, versions 3.0, 3.0b, 5.0, 5.0a, 6.0 
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SYMPTOMS
========

When the stored value is smaller than 10 to the minus (-)15th power, the new
data type, known as double, is not displayed correctly in a table field.

Visual FoxPro should display numbers smaller than 10 to the -15th power. For
example, the number 0.00000000000000009 (9 x 10 to the -17th power) should be
displayed as 9.0000000000000E-17. You see this as .0000000000000000000 in a
browse.

In Visual FoxPro versions 3.0 and 3.0b, values smaller than 10 to the -15th power
are displayed as a string of zeros.

In Visual FoxPro 5.0, values between 10 to the -15th power and 10 to the -30th
power are displayed as zeros. Values smaller than 10 to the -30th power are
displayed correctly. For example, 9 x 10 to the -32nd power is displayed
correctly as 9.0000000000000E-32.

Values between 10 to the -13th power and 10 to the -15th power may also appear
incorrectly.

STATUS
======

Microsoft has confirmed this to be a problem in the Microsoft products listed at
the beginning of this article.

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

The values are stored correctly, but displayed incorrectly. Arithmetic
operations that use the values are performed correctly. To see the values, you
must multiply them by a positive power of 10. As a result, the significant
digits are within the range of values that are displayed correctly.

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

Visual FoxPro 3.0, 3.0b, and 5.0 may display the following commands in the
Command window:

     CREATE TABLE dpt (dp B(18))     && Double data, 18 to right of decimal
     INSERT INTO dpt (dp) VALUES (9)
     BROWSE     &&; The data appears as a 9, a decimal, and 18 zeros
     REPLACE dp WITH dp/10**15  && 0. then 14 zeros followed by 9000
     REPLACE dp WITH dp/10      && 0. then 14 zeros followed by 1000
     REPLACE dp WITH 9          && Reset
     REPLACE dp WITH dp/10**31  && Correct in version 5, wrong in version 3.x
     REPLACE dp WITH dp/10**277 && Correct in version 5, zeros in version 3.x
     REPLACE dp WITH dp*10**308 && Restores 9.00000000000000000

Additional query words: kbvfp300 kbvfp300b kbvfp500 kbvfp500a kbvfp600

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Keywords          : kbvfp kbvfp300bBUG kbvfp500aBUG kbvfp500bug kbbuglist
Technology        : kbVFPsearch kbAudDeveloper kbVFP300 kbVFP300b kbVFP500 kbVFP600 kbVFP500a
Version           : WINDOWS:3.0,3.0b,5.0,5.0a,6.0
Issue type        : kbbug

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