Q32270: COMMON Variable Has Different Value with .EXE Versus QB.EXE

Article: Q32270
Product(s): See article
Version(s): 4.00 4.00b
Operating System(s): MS-DOS
Keyword(s): ENDUSER | buglist4.00 buglist4.00b fixlist4.50 B_BasicCom | mspl13_basic
Last Modified: 13-DEC-1989

If a variable in COMMON and a variable in the body of a program have
the same name but a different type specifier (%, !, #, or &), the
QuickBASIC environment may make incorrect assumptions about the type,
compared to the resulting .EXE file. An example is shown below, where
the value of a variable is different when run in QB.EXE versus the
compiled .EXE program.

Microsoft has confirmed this to be a problem in QuickBASIC Versions
4.00 and 4.00b, and the QuickBASIC Compiler provided with BASIC
compiler Versions 6.00 and 6.00b for MS-DOS and MS OS/2 (buglist6.00,
buglist6.00b). The problem does not occur with programs compiled with
BC.EXE. This problem was corrected in QuickBASIC Version 4.50 and in
the QBX.EXE environment of Microsoft BASIC PDS Version 7.00
(fixlist7.00).

The following program produces different results with BC.EXE versus
QB.EXE:

   COMMON SHARED A
   A%=5
   CALL TEST
   END

   SUB TEST STATIC
     PRINT A
   END SUB

When compiled with BC.EXE, the program correctly displays 0. When run
in QB.EXE, the program incorrectly displays 5.

This problem occurs because QB.EXE works on the premise that you
really wanted the variable A in COMMON to be an integer instead of
single precision.

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