Q32100: RANDOMIZE Results Differ in QB.EXE Versus Compiled .EXE

Article: Q32100
Product(s): See article
Version(s): 4.00 4.00b 4.50
Operating System(s): MS-DOS
Keyword(s): ENDUSER | buglist4.00 buglist4.00b fixlist4.50 B_BasicCom | mspl13_basic
Last Modified: 8-DEC-1989

The RANDOMIZE statement gives different results inside the QuickBASIC
(QB.EXE) environment from the results it gives in an executable file
(.EXE) using the same seed. This difference poses a problem for
software developers using the QB.EXE environment who depend upon a
given seed for the RANDOMIZE statement to make the RND function return
the same series of random numbers as a compiled .EXE program.

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

This problem does not occur in QuickBASIC Version 3.00; the results
obtained from within the QuickBASIC Version 3.00 environment and the
results from the executable program are the same. Note: The differing
random-number series using the same seed between QuickBASIC Version
3.00 and Version 4.00 is expected and is not considered to be a
problem.

When a program is executed several times (with the same seed for the
RANDOMIZE statement) from a given environment, the RND function
returns the same number series every time (in all versions of
Microsoft BASIC), which is expected behavior.

The following code demonstrates the problem:

RANDOMIZE 1000
FOR i = 1 TO 10
        PRINT INT(RND * 10) + 1
NEXT i
END

The following are the results (every time) when executed from inside
the QuickBASIC Version 4.00b QB.EXE editor:

   7
   2
   4
   3
   2
   5
   1
   5
   4
   7

The following are the results (every time) when executed from the .EXE
file created by QuickBASIC Version 4.00b:

   8
   5
   7
   6
   2
  10
   3
   4
   7
   8

The following are the results (every time) when executed from
QuickBASIC Version 3.00 or an executable file compiled in Version
3.00:

  10
   7
  10
   4
   3
   4
  10
   1
   3
   4

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