Q112333: FIX: CTRL+Z Is Not End-of-File Marker in PowerStation

Article: Q112333
Product(s): Microsoft Fortran Compiler
Version(s): 1.0,1.0a
Operating System(s): 
Keyword(s): kbFortranPS kbLangFortrankbbuglist 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
========

Run-time error F6101 or F6103 (invalid INTEGER or invalid REAL) may be generated
on reading from the last record in a file using Microsoft FORTRAN PowerStation.

CAUSE
=====

The CTRL+Z character is not treated as the true end-of-file marker in MS-DOS or
Windows. This character is interpreted as a nonstandard character by FORTRAN
PowerStation in many circumstances.

RESOLUTION
==========

To resolve this problem, remove the CTRL+Z character from the end of data files.
The function NO_CTRLZ provided below may be used to do this for any file with or
without the CTRL+Z character.

STATUS
======

Microsoft has confirmed this to be a problem in Microsoft FORTRAN PowerStation
32 version 1.0 and 1.0a for MS-DOS and version 1.0 for Windows NT. This problem
was corrected in FORTRAN PowerStation 32, version 4.0.

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

To demonstrate the problem:

1. Build MAKEDATA.FOR and READDATA.FOR (no options are needed).

2. Run MAKEDATA to create a data file ending in a CTRL+Z character.

3. Run READDATA to generate the error:

  run-time error F6101: READ(z-test.dat)
  - invalid INTEGER

4. To fix the data file, build STRIP:

        FL32 strip.for no_ctrlz.for

5. Run STRIP (which uses NO_CTRLZ to remove the CTRL+Z):

        STRIP z-test.dat

6. Run READDATA again (no error will be generated).

Sample Code MAKEDATA.FOR
------------------------

  C Compile options needed: None
        open(10, file='z-test.dat',form='BINARY')
        write(10) '1234', char(26)
        end

Sample Code READDATA.FOR
------------------------

  C Compile options needed: None

        open(10,file='z-test.dat')
        do i=1,20
           read(10,*,end=9) k
           print *, k
        enddo

     9  end

Sample Code STRIP.FOR
---------------------

  C Compile options needed: None
  C To build it use: "FL32 STRIP.FOR NO_CTRLZ.FOR"
        include 'flib.fi'
        include 'flib.fd'

        character *40 filename
        integer*2 i

        if (NARGS() .gt. 1) then
          call getarg(1, filename, i)
          i = no_ctrlz(filename)
          if (i .ne. 0) then
            print *, 'Could not open the file: ', filename
          end if
        end if

        end

Sample Code NO_CTRLZ.FOR
------------------------

  C Compile options needed: None
  c     NO_CTRLZ removes the last character in a file if it is CTRL+Z
  c
  c     Returns 1 if there are problems, otherwise 0.
  c

        integer function no_ctrlz(filename)
        character c, filename*(*)
        logical exist

        inquire(file=filename(:len_trim(filename)),EXIST=exist)
        if (.not. exist) then
          no_ctrlz = 1
          return
        end if

        open(10,file=filename(:len_trim(filename)),access='APPEND',
       +  form='BINARY',recl=1)

  c     Check if the last character is CTRL+Z
        backspace(10)
        read(10) c
        if (ichar(c) .ne. 26) then
          no_ctrlz = 0 !No error, just don't need to do anything
          return
        end if

  c     Backup, and then rewrite the next to last character to reset
  c     the true end-of-file marker.
        backspace(10)
        backspace(10)
        read(10) c
        backspace(10)
        write(10) c

        close(10)

        no_ctrlz = 0  !COMPLETED SUCCESSFULLY

        end

Additional Reference Words: 1.00 ctrl-z

Additional query words:

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

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

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY.

Copyright Microsoft Corporation 1986-2002.