Q130807: BUG: READ w/ Numeric Literal Subscript Causes Access Violation

Article: Q130807
Product(s): Microsoft Fortran Compiler
Version(s): 1.0
Operating System(s): 
Keyword(s): 
Last Modified: 03-NOV-1999

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The information in this article applies to:

- Microsoft Fortran Powerstation 32 for Windows NT, version 1.0 
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SYMPTOMS
========

Exporting an array in a COMMON block from a dynamic-link library (DLL) and
attempting to read a member of the array by using a numeric literal as a
subscript in the READ statement may generate an access violation.

RESOLUTION
==========

Here are two ways to work around this problem:

- Use INTEGER variables instead of numeric literals as subscripts when
  accessing COMMON arrays.

-or-

- Read exported COMMON data into local allocatable arrays. Then assign these
  arrays to the arrays in the exported COMMON block.

STATUS
======

Microsoft has confirmed this to be a bug in the Microsoft products listed at the
beginning of this article. We are researching this problem and will post new
information here in the Microsoft Knowledge Base as it becomes available.

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

This error occurs only with READ statements. It does not occur with WRITE
statements or when reading COMMON variables.

Sample Code to Reproduce Problem
--------------------------------

  C  The code for the DLL
  C  Compile options needed: /LD
  C
         COMMON /TheBlock[DLLEXPORT]/ CommonBlockIntegerArray(3)
         INTEGER*4 CommonBlockIntegerArray
            CommonBlockIntegerArray(1) = 1
            CommonBlockIntegerArray(2) = 2
            CommonBlockIntegerArray(3) = 3
         END
  C
  C  The code for the EXE.
  C  Compile options needed: none
  C  Linker options needed: include the import library for the DLL
  C
  C  Define the common block for sharing.
  C
        COMMON /TheBlock[DLLIMPORT]/ CommonBlockIntegerArray(3)
        INTEGER*4 CommonBlockIntegerArray
  C
  C  Some local variables.
  C
        INTEGER*4 intTemp
        CHARACTER*3 someText
  C
  C  The main program.
  C
        someText = '11'
        intTemp = 1
  C
  C  If the subscript is an integer variable, there is no problem.
  C
        READ (someText, '(A3)') CommonBlockIntegerArray(intTemp)
  C
  C  The array subscript is a numeric literal, an access violation occurs.
  C
        READ (someText, '(A3)') CommonBlockIntegerArray(1)
        END

REFERENCES
==========

For information on a related problem, please see the following article in the
Microsoft Knowledge Base:

  Q112010 BUG: Access Violation on READ of Exported COMMON Array

Additional query words: 1.00 Dr. Watson imported

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Keywords          :  
Technology        : kbAudDeveloper kbFortranSearch kbZNotKeyword2 kbFORTRANPower32100NT
Version           : :1.0

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