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

MS-DOS      | WINDOWS NT

The information in this article applies to:

• Microsoft FORTRAN PowerStation for MS-DOS, version 1.0 and 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)

      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