DOCUMENT:Q155622  04-AUG-2001  [visualc]
TITLE   :FIX: IDE Debugger Truncates Floating Point Numbers
PRODUCT :Microsoft C Compiler
PROD/VER:winnt:
OPER/SYS:
KEYWORDS:kbProgramming kbDebug kbide kbVC400bug kbVC410bug kbVC420bug kbVC500fix

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The information in this article applies to:

 - The Integrated Debugger, included with:
    - *EDITOR Please do not choose this product*Microsoft Visual C++ 32-bit Edition* use 241, 265, 225, versions 4.0, 4.1, 4.2 
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SYMPTOMS
========

If you change the Language Settings under the operating system to a language
that uses a comma as the decimal separator, recalculating any floating point
numbers in the QuickWatch window in the integrated debugger truncates the
floating point number. Thereafter, incorrect results may be generated from
program execution. To reproduce the problem, please see the "More Information"
section below.

The following language settings may cause this problem.

   German      Italian    Portuguese    Swedish   Norwegian
   Indonesian  Icelandic  French        Finnish   Dutch
   Danish      Catalan    Basque

RESOLUTION
==========

To work around the problem, use one of the following suggestions:

 - In the QuickWatch window, cast the variable you plan to watch to the proper
   type. For example, if you plan to watch variable "a" in the following
   program, because "a" is defined as type double, cast it to a double in the
   QuickWatch window. That is, type "(double)a" (without the quotation marks) in
   the QuickWatch window.

   -or-

 - In the QuickWatch window, add zero to the variable. For example, in the
   following program, type "a+0" (without the quotation marks) in the QuickWatch
   window to watch variable "a".

STATUS
======

Microsoft has confirmed this to be a bug in the Microsoft products listed at the
beginning of this article. This bug was corrected in Visual C++ version 5.0.

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

You can use the following steps to reproduce the problem:

1. Use Control Panel to change language settings to German(Standard), then
   reboot the system.

2. Build an application using the source file below:

      /* Compile options needed: Developer Studio default console application
      */ 

      #include <stdio.h>

      void main()
      {
         double a = 1.99;
         double b;

         printf("a = %g\n", a);

         b = a;  // At this point do QuickWatch and Recalculate for 'a'.

         printf("b = %g\n", b);
      }

3. Start debugging and get to the commented line "b = a".

4. Use QuickWatch for "a"; it will show the correct value 1.99.

5. Click Recalculate one or two times more.

Result: The value of "a" is changed to 1.0, and the program's output will be
wrong when execution is continued to next line.


Additional query words:

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Keywords          : kbProgramming kbDebug kbide kbVC400bug kbVC410bug kbVC420bug kbVC500fix 
Technology        : kbVCsearch kbAudDeveloper kbIntegratedDebugger
Version           : winnt:
Issue type        : kbbug
Solution Type     : kbfix

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

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