Q45545: QB Debugger Step Problem with Breakpoint in Watched FUNCTION

Article: Q45545
Product(s): See article
Version(s): 4.00 4.00b 4.50
Operating System(s): MS-DOS
Keyword(s): ENDUSER | buglist4.00 buglist4.00b buglist4.50 B_BasicCom | mspl13_basic
Last Modified: 20-SEP-1990

The Step (press F8) command in the QuickBASIC version 4.50 editor may
not operate correctly when all of the following conditions are met:

1. You declared and defined a FUNCTION procedure.
2. You chose Add Watch or Instant Watch on the FUNCTION name.
3. You set a breakpoint inside the FUNCTION procedure being watched.

The symptom of the problem is that when the Step process (F8) begins,
it causes the watched FUNCTION to be executed from the beginning to
the breakpoint, instead of executing intervening lines individually
with each press of the F8 key. Choosing Restart from the Run menu or
pressing F8 again causes the editor to again step through the FUNCTION
from the beginning to the breakpoint.

Microsoft has confirmed this to be a problem in the QB.EXE environment
of Microsoft QuickBASIC versions 4.00, 4.00b, and 4.50; in the QB.EXE
environment of Microsoft BASIC compiler versions 6.00 and 6.00b
(buglist6.00, buglist6.00b); and in the QBX.EXE environment of
Microsoft BASIC Professional Development System (PDS) versions 7.00
and 7.10 for MS-DOS (buglist7.00, buglist7.10). We are researching
this problem and will post new information here as it becomes
available.

To work around this problem, either remove the breakpoint from the
watched FUNCTION, or delete the watch on the FUNCTION.

Code Example
------------

After you choose Add Watch on test% and set a breakpoint on the PRINT
"world" line, the following code example executes the FUNCTION test%
from the beginning to the PRINT "world" line when you perform a Step
(F8) operation:

   DECLARE FUNCTION test% ()
   x% = test%
   END

   FUNCTION test%     'Add Watch... on test%
     PLAY "CDEFGAB>C"   'These two lines are executed
     PRINT "Hello"      'on every Step (F8)
     PRINT "world"    'Set Breakpoint here
     ' Never gets here
     test% = 1
   END FUNCTION

To work around this problem, Add Watch on x% instead of test%, or
remove the breakpoint.

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.