FIX: READ Gets Bad Data After Exit Error

The information in this article applies to:

• Microsoft FORTRAN for MS-DOS, version 5.1

SYMPTOMS

If you attempt to do a READ from a file after another READ has exited during an error, the data you obtain will be bad.

STATUS

Microsoft has confirmed this to be a bug in FORTRAN, version 5.1. This problem was corrected in FORTRAN PowerStation for MS-DOS, version 1.0.

MORE INFORMATION

When you read from a file, the READ statement transfers control to another line if the "err=" is included and there is a read error. If another READ is attempted immediately, the variables in the iolist contain bad data, usually 0.

If your data file looks like

   11.
   ***
   22.
   33.

   Normal print after read 1.  iostat=       0  data(1):      11.000000
   Error from read 2.
   Normal print after read 3.  iostat=       0  data(3):      22.000000
   Normal print after read 4.  iostat=       0  data(4):      33.000000
   Printing out data
   data(          1) =       11.000000
   data(          2) =       99.000000
   data(          3) =       22.000000
   data(          4) =       33.000000
   Stop - Program terminated.

   Normal print after read 1.  iostat=       0  data(1):       11.000000
   Error from read 2.
   Normal print after read 3.  iostat=       0  data(3):    0.000000E+00
   Normal print after read 4.  iostat=       0  data(4):       22.000000
   Printing out data
   data(          1) =       11.000000
   data(          2) =       99.000000
   data(          3) =    0.000000E+00
   data(          4) =       22.000000
   Stop - Program terminated.

Sample Code

C Compile options needed: none

      REAL*4 data(4)
      DATA data /4*99./

      OPEN(15, file="Data")

      READ(15, "(f3.0)", ERR=10, END=90, IOSTAT=i) data(1)
      PRINT*, "Normal print after read 1.  ",
     +"iostat=", i, "  data(1): ", data(1)
      GOTO 15
   10 PRINT*, "Error from read 1."

   15 READ(15, "(f3.0)", ERR=20, END=90, IOSTAT=i) data(2)
      PRINT*, "Normal print after read 2.  ",
     +"iostat=", i, " data(2): ", data(2)
      GOTO 25
   20 PRINT*, "Error from read 2."

   25 READ(15, "(f3.0)", ERR=30, END=90, IOSTAT=i) data(3)
      PRINT*, "Normal print after read 3.  ",
     +"iostat=", i, "  data(3): ", data(3)
      GOTO 35
   30 PRINT*, "error from read 3"

   35 READ(15, "(f3.0)", ERR=40, END=90, IOSTAT=i) data(4)
      PRINT*, "Normal print after read 4.  ",
     +"iostat=", i, "  data(4): ", data(4)
      goto 999
   40 PRINT*, "error from read 4"
      GOTO 999

   90 PRINT*, "End of file jump."

  999 PRINT*, "Printing out data"
      DO 1000 i = 1, 4
          PRINT*, "data(",i,") = ", data(i)
 1000 CONTINUE

      STOP
      END