FIX: Tab Edit Descriptor Fails Crossing Buffer Boundary

MS-DOS    | OS/2

The information in this article applies to:

• Microsoft FORTRAN for MS-DOS, versions 5.0 and 5.1
• Microsoft FORTRAN for OS/2, versions 5.0 and 5.1

SYMPTOMS

When the following conditions are met

1. Output is placed in a record position that is beyond the number of bytes held by the I/O buffer.

2. The FORMAT edit descriptor tabs back to a position that is within the number of bytes held by the I/O buffer.

3. Output is written on top of the existing output that is immediately after the I/O buffer boundary.

RESOLUTION

Since it is difficult to determine if a tab operation is going to cross an I/O buffer boundary, it is best to avoid tabbing back behind and overwriting existing output in a record. If the size of the I/O buffer is increased to a larger number, there will be fewer buffer boundaries and the probability of encountering this problem will be decreased.

STATUS

Microsoft has confirmed this to be a bug in the products listed above. This problem was corrected in FORTRAN PowerStation, version 1.0.

MORE INFORMATION

The following code can be used to reproduce the problem:

Sample code

       open(1,file='test.dat',blocksize=1024)
       write(1,10) '@@@@@@@@@@@@@@',123,456,789

       end

123     @@@         789