Q114979: BUG: Access Violation or R6018 Executing IF Statement

Article: Q114979
Product(s): Microsoft Fortran Compiler
Version(s): 1.0,1.0a
Operating System(s): 
Keyword(s): 
Last Modified: 02-NOV-1999

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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 
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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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