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Q103036: BUG: AddAtom Causes Divide by Zero Error

Article: Q103036
Product(s): Microsoft Windows Software Development Kit
Version(s): WINDOWS:3.1
Operating System(s): 
Keyword(s): 
Last Modified: 06-NOV-1999

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The information in this article applies to:

- Microsoft Windows Software Development Kit (SDK) 3.1 
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SYMPTOMS
========

Calling the AddAtom function in the Windows 3.x environment with a string that
begins with the pound (#) character causes the system to display the following
error message in a system modal dialog:

  Application Error

  integer divide by 0

This error occurs if the first AddAtom call in the application passes a string
containing a # as the first character, and passes non-numeric characters in the
rest of the string. For example, the first call to AddAtom with the string
"#string" will cause the error to occur.

RESOLUTION
==========

If it is necessary to have atom strings beginning with the # character, first
call AddAtom with a false string that contains no # characters. Alternatively,
call InitAtomTable before adding the first atom string beginning with the #
character.

STATUS
======

Microsoft has confirmed this to be a bug in Windows versions 3.0 and 3.1. We are
researching this problem and will post new information here in the Microsoft
Knowledge Base as it becomes available.

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

Atoms with names begin with the # character are strongly discouraged. The #
character serves a special purpose for atoms. If the string that is passed to
AddAtom has the form "#1234", AddAtom returns an integer atom whose value is the
16-bit value representation of the decimal number specified in the string. If
the decimal value specified is 0 (zero) or a value in the range 0xC000 through
0xFFFF, the return value is zero, indicating an error.

Sample Code
-----------

  /* Compile options needed:  /Zp /GA or /GD or /Gw */ 

  // errant code
  {
   ATOM at;

   at = AddAtom("#string");     // causes error to occur

  }

  // corrected code
  {
   ATOM at;

   InitAddTable(17);

   // or call AddAtom with a false string

   AddAtom("false");

   at = AddAtom("#string");     // no error occurs

  }

Additional query words: 3.00 3.10

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Keywords          :  
Technology        : kbAudDeveloper kbWin3xSearch kbSDKSearch kbWinSDKSearch kbWinSDK310
Version           : WINDOWS:3.1

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