unformatted read/writes

[Justin_v_]

My application has recently stopped being able to read unformatted files that are greater than 2.1GB in size.  Specifically, the read command of the following subroutine fails (iostat=-1) if jj = 2900 (file size 2.15GB), but works (iostat=0) if jj=2800 (file size 2.08GB).

ii = 95000
jj = 4000
allocate ( store_huge(ii, jj), STAT = istat )
store_huge = 0.0

open( newunit = file_id, file = outputfilename, form = 'unformatted', action='write', iostat = istat )
write(file_id, IOSTAT=istat) store_huge
close(file_id)

store_huge = 1.0
open(newunit=file_id, FILE=outputfilename, form = 'unformatted', action='read', iostat = istat)
read(file_id, IOSTAT=istat) store_huge
close(file_id)

deallocate( store_huge )

This problem only appeared recently, and may be due to a recent Windows update (which we can no longer control, and which have been driving me crazy).  I have Windows 10 (including the most recent automated updates), am using VS2017 (which may be the problem, though I have been using this for a couple of months without issue), and Visual Fortran Compiler 17.0.4.210.

[Justin_v_]

andrew_4619 wrote:

And now I am confused as the examples in this thread use real(8) and not the defunct real*8. I don't get Surely removing IOSTAT=  that means I program crashes on error rather than you being able to handle the error.

Running a program from the command window sometimes generates useful run-time detail on a crash - but in this case, the IOSTAT already seemed to be pretty clear.

I will try to be more careful in the future, when copying code snippets to the forum.

[andrew_4619]

Ok, not confused now.....