Q42473: "Overflow" Error Might Be the Result of 0/0

Article: Q42473
Product(s): See article
Version(s): 4.00 4.00b 4.50
Operating System(s): MS-DOS
Keyword(s): ENDUSER | SR# S890309-179 B_BasicCom | mspl13_basic
Last Modified: 13-DEC-1989

When the error "Overflow" is encountered in a Microsoft QuickBASIC
program, one possibility is to check for a zero divided by zero (0/0)
condition.

This information applies to Microsoft QuickBASIC Versions 4.00, 4.00b,
and 4.50 for MS-DOS; to Microsoft BASIC Compiler Versions 6.00 and
6.00b for MS-DOS and MS OS/2; and to Microsoft BASIC PDS Version 7.00
for MS-DOS and MS OS/2.

Any numeric value divided by zero will produce the error "Division By
Zero," but zero (0) being divided by zero produces a special floating-
point exception. This error will cause the compiler to respond with an
"Overflow" message.

Both of these errors are correct. The machine could respond by either
a "Division By Zero" error or an "Overflow" error, depending on the
following factors:

1. Is the computer using a coprocessor?

2. Is the coprocessor functioning correctly?

3. What operating system are you using? (There was a problem with
   PC-DOS Version 3.20.)

When diagnosing an "Overflow" error, you may wish to first determine
if the expression reduces to zero divided by zero. This might save you
work trying to figure out why your expression is overflowing (or
exceeding some numerical limit).

The following is a code example:

b# = 5
c# = 5
PRINT (b#-c#) / (b#-c#) ' This will result in an "Overflow" error

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY.

Copyright Microsoft Corporation 1986-2002.