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Q185280: FIX: Printf Gives Unexpected Results for Doubles on WinCE

Article: Q185280
Product(s): Microsoft C Compiler
Version(s): WINDOWS:1.0
Operating System(s): 
Keyword(s): kbfix
Last Modified: 10-MAY-2001

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

- Microsoft Visual C++ for Windows CE, version 1.0 
-------------------------------------------------------------------------------

SYMPTOMS
========

When you use any of the printf C run-time routines (printf, _vstprintf,
_stprintf, and so on) with the "%f" format specifier, you get unexpected
results. The printf C run-time routines return the floating-point format
specifier without the leading '%' instead of the text representation of the
number. For example, the following code gives the result "f" instead of
"1.23456789":

     _stprintf(pBuffer, TEXT("%f"), 1.23456789);

CAUSE
=====

This is a bug in the printf C run-time routines. The printf routines for Windows
CE do not support floating-point numbers.

RESOLUTION
==========

This has been fixed in version 2.0 of Visual C++ for Windows CE. To work around
this problem in version 1.0, you must manually convert the floating- point
number. You can use the _gcvt function to convert the floating-point number to
an ANSI string, and then use the "%S" format specifier in a printf routine to
convert the ANSI string to UNICODE.

For example, replace the following code:

     _stprintf(pBuffer, TEXT("%f"), 1.23456789);

with:

     char pTemp[256];
     _gcvt(1.23456789,9,pTemp);
     _stprintf(pBuffer, TEXT("%S"), pTemp);

STATUS
======

Microsoft has confirmed this to be a bug in the Microsoft products listed at the
beginning of this article. This bug has been corrected in Visual C++ for Windows
CE, 2.0.

Additional query words: kbnokeyword kbwince100fix

======================================================================
Keywords          : kbfix 
Technology        : kbVCsearch kbAudDeveloper kbZNotKeyword3 kbVC100WinCE
Version           : WINDOWS:1.0
Issue type        : kbbug
Solution Type     : kbfix

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