DOCUMENT:Q103036  06-NOV-1999  [win16sdk]
TITLE   :BUG: AddAtom Causes Divide by Zero Error
PRODUCT :Microsoft Windows Software Development Kit
PROD/VER:WINDOWS:3.1
OPER/SYS:
KEYWORDS:

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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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