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copied!<p>Firstly, I do not think you need to close and reopen your output file as you are doing. The <code>status</code> specifier is only relevant to the <code>open</code> statement in which it appears: <code>replace</code> will delete <code>Newfile.bin</code> if it exists at that time, before opening a new file with the same name. The status is implicitly changed to <code>old</code>, but this does not affect any operations done to the file.</p> <p>However, since your Fortran code does not know you run it 12 times, you should have a way of making sure the file is only replaced the first time and opened as <code>old</code> afterwards; otherwise, <code>Newfile.bin</code> will only contain the information from the last file processed.</p> <p>As for reading in the wrong values, this most likely occurs because of the difference between direct access (where you can choose a record length) and stream access (where you cannot). With stream access, data is stored as a sequence of "file storage units". Their size is in general compiler-dependent, but is available through the module <code>iso_fortran_env</code> as <code>file_storage_size</code>; it is usually 8 bits. This means that each entry will usually occupy multiple storage units, so you have to take care that a read or write with the <code>pos =</code> specifier does not access the wrong storage units.</p> <hr> <p><strong>Edit:</strong><br> Some example code writing and reading with stream access:</p> <pre><code>program stream use, intrinsic :: iso_fortran_env implicit none integer :: i, offset real(real32), dimension(4,6) :: val, nval open(unit=2, file='Newfile.bin', action='readwrite', form='unformatted', & access='stream', status='replace') do i = 1,2 call random_number(val) write(2) val enddo ! The file now contains two sequences of 24 reals, each element of which ! occupies the following number of storage units: offset = storage_size(val) / file_storage_size ! Retrieve the second sequence and compare: read(2, pos = 1 + offset*size(val)) nval print*, all(nval == val) close(2) end program </code></pre> <p>The value <strong>true</strong> should be printed to the screen.</p> <p>Note also that it's not strictly necessary to specify a <code>pos</code> while writing your data to the file, because the file will automatically be positioned beyond the last record read or written.</p> <hr> <p>That said, direct or stream access is most beneficial if you need to access the data in a non-sequential manner. If you only need to combine input files into one, it could be easier to write the output file with sequential access, for which you can also specify <code>recl</code> and <code>position = 'append'</code>.</p>

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