Q30314: PRINT SGN(a) AND SGN(b) Fails If Compiled with BC.EXE; 4.50 OK

Article: Q30314
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: 31-JAN-1990

The following statement fails to correctly output a zero (0) at run
time when compiled with BC.EXE; however, it correctly outputs a zero
in the QB.EXE interpreter:

   PRINT (SGN(a)) AND (SGN(b))

Microsoft has confirmed this to be a problem in QuickBASIC Versions
4.00 and 4.00b, and in Microsoft BASIC Compiler Versions 6.00 and
6.00b for MS-DOS and OS/2 (buglist6.00, buglist6.00b). This problem
was corrected in QuickBASIC Version 4.50 and in Microsoft BASIC
Professional Development System (PDS) Version 7.00 for MS-DOS and MS
OS/2 (fixlist7.00).

The following is a workaround for this problem:

1. Assign SGN(a) and SGN(b) to intermediate variables.

2. Use the intermediate variables in the AND operation as follows:

      x = SGN(a)
      y = SGN(b)
      PRINT (x) AND (y)

When compiled with QuickBASIC Version 3.00, the correct output is
generated when run from an EXE program or inside the QB.EXE editor.

The following is a code example showing the problem:

'It should print  0  -1   0  but the AND does not work with BC.EXE:
a = 0
b = -1
PRINT SGN(a),
PRINT SGN(b),
PRINT (SGN(a)) AND (SGN(b))

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