DOCUMENT:Q114979  02-NOV-1999  [fortran]
TITLE   :BUG: Access Violation or R6018 Executing IF Statement
PRODUCT :Microsoft Fortran Compiler
PROD/VER::1.0,1.0a
OPER/SYS:
KEYWORDS:

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

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

SYMPTOMS
========

For FORTRAN PowerStation 32, an access violation occurs and for FORTRAN
PowerStation, runtime error R6018 and an unexpected heap error occur when you
execute code where:

 - There is an IF statement alone (not "IF... THEN...").

.  - There is a call to a subroutine that takes a character argument in the IF
   block.

 - The actual argument passed to the subroutine is a character expression that
   includes concatenation of characters.

 - The IF expression is evaluated as ".FALSE" so that the call is not carried
   out.

RESOLUTION
==========

Use one of the following to work around the problem:

 - Use a block IF (that is, "IF... THEN ...") rather than an IF statement alone.

-or-

 - Assign the character expression to a temporary variable instead of passing it
   directly to the subroutine.

STATUS
======

Microsoft has confirmed this to be a bug in Microsoft FORTRAN PowerStation,
version 1.0a for MS-DOS and version 1.0 for Windows NT. We are researching this
problem and will post new information here in the Microsoft Knowledge Base as it
becomes available.

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

To reproduce the problem, compile and run the following sample code:

Sample Code
-----------

   C compile options needed: none

            CHARACTER*80 A
            CHARACTER*3 end
            LOGICAL L
            end  = 'End'
            L = .FALSE.
      C1      L = .TRUE.
            A = 'This format bombs...'//end
      C2      IF (L)  print *, A
            IF (L)  print *, 'This format bombs...'//end
      C3      IF (L) then
      C3        print *, 'This format bombs...'//end
      C3      end if
            print *, end
            END

To run the program without error:

 - Uncomment C1.

-or-

 - Comment out the single line "IF" and uncomment C2.

-or-

 - Comment out the single line "IF" and uncomment C3.

Additional query words: 1.00 1.00a

======================================================================
Keywords          :  
Technology        : kbAudDeveloper kbFortranSearch kbZNotKeyword2 kbZNotKeyword3 kbFORTRANPower32100NT kbFORTRANPower100aDOS
Version           : :1.0,1.0a

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

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