Q155622: FIX: IDE Debugger Truncates Floating Point Numbers
Article: Q155622
Product(s): Microsoft C Compiler
Version(s): winnt:
Operating System(s):
Keyword(s): kbProgramming kbDebug kbide kbVC400bug kbVC410bug kbVC420bug kbVC500fix
Last Modified: 04-AUG-2001
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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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