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Q109874: FIX: Constants Out of Range Not Found by /4Yb

Article: Q109874
Product(s): Microsoft Fortran Compiler
Version(s): 1.0,1.0a
Operating System(s): 
Keyword(s): kbCompiler kbFL32 kbFortranPSkbbuglist kbfixlist
Last Modified: 24-MAR-2000

-------------------------------------------------------------------------------
The information in this article applies to:

- Microsoft FORTRAN PowerStation for MS-DOS, versions 1.0, 1.0a 
- Microsoft Fortran Powerstation 32 for Windows NT, version 1.0 
-------------------------------------------------------------------------------

SYMPTOMS
========

A program that contains a simple arithmetic expression including constant out of
range may produce incorrect results. Using the -4Yb compiler option does not
give a run-time error on constants that are out of range even though it should.

CAUSE
=====

The constant folding algorithm (arithmetic performed at compile time) generates
0 (zero) for the variable out of range.

RESOLUTION
==========

Avoid using a simple constant expression that might be out of range. Use the
temporary variable for the intermediate results and then use this variable in
the expression. Compile the program with -4Yb and the appropriate run-time error
will be generated.

STATUS
======

Microsoft has confirmed this to be a problem in Microsoft FORTRAN PowerStation
32 for NT, version 1.0 and FORTRAN Powerstation for MS-DOS version 1.0 and 1.0a.
This is not a problem in Microsoft FORTRAN for MS-DOS, version 5.1, or FORTRAN
PowerStation 32, version 4.0.

MORE INFORMATION
================

Sample Code #1
--------------

  c Compile options required: -4Yb does not affect the behavior
  c The following code reproduces the problem.

         i=2**50
         write (*,*) i
         end

Sample Code #2
--------------

  c Compile options required: -4Yb
  c The following code solves the problem and generates the following
  c run-time error: run-time  F6099: $DEBUG
  c            -INTEGER arithmetic overflow

         j=50
         i=2**j
         write (*,*) i
         end

Additional query words: 1.00 runtime run time

======================================================================
Keywords          : kbCompiler kbFL32 kbFortranPS kbbuglist kbfixlist
Technology        : kbAudDeveloper kbFortranSearch kbZNotKeyword2 kbZNotKeyword3 kbFORTRANPower32100NT kbFORTRANPower100DOS kbFORTRANPower100aDOS
Version           : :1.0,1.0a
Issue type        : kbbug
Solution Type     : kbfix

=============================================================================

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