Q28977: /MBF Fails When Variable x Used in Random file PUT#1,,x

Article: Q28977
Product(s): See article
Version(s): 4.00 4.00b
Operating System(s): MS-DOS
Keyword(s): ENDUSER | B_BasicCom buglist4.00 buglist4.00b fixlist4.50 | mspl13_basic
Last Modified: 31-JAN-1990

Programs compiled with the /MBF switch are not compatible with the new
PUT syntax where a variable can be specified as the third parameter
(PUT#n,,x).

When a program compiled with the /MBF switch creates a random access
file using the PUT statement with a variable in the third argument,
the data file is not correctly read by subsequent programs which are
also compiled with /MBF.

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 MS 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).

This problem can be re-created by doing the following:

1. Create a random access file with the following program:

      ' MKTEST.BAS - Compiled with /MBF option

      OPEN "r", 1, "test.dat"
      FOR n = 1 TO 5
      PUT #1, n, n
      NEXT
      CLOSE #1

2. Read the data file TEST.DAT with the following program:

       ' RDTEST.BAS - Compiled with /MBF option

       OPEN "r", 1, "test.dat"
       FIELD #1, 4 AS a$
       FOR n = 1 TO 5
       GET #1, n
       PRINT CVS(a$)
       NEXT
       CLOSE #1

If the following printed output does not appear from RDTEST.BAS, the
output is incorrect:

   1 2 3 4 5

However, if RDTEST.BAS is not compiled with the /MBF option (while
MKTEST.BAS is still compiled with /MBF), the output is correct.

One workaround is to avoid using the new variable (third) parameter
with the PUT statement. This implies that a FIELD statement must be
used in conjunction with the older two-argument PUT syntax. The above
MKTEST.BAS would be modified in the following manner (it must be
compiled with the /MBF switch):

   OPEN "r", 1, "test.dat"
   FIELD #1, 4 AS a$
   FOR i = 1 TO 5
   LSET a$ = MKS$(i)
   PUT #1, i
   NEXT i
   CLOSE #1
   END

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