Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!rice!rice!sun-spots-request
From: pln@sage0.gsfc.nasa.gov (Pat Nolan)
Newsgroups: comp.sys.sun
Subject: Reading variable-length records in Sun Fortran
Keywords: Miscellaneous
Message-ID: <1990Oct7.225430.950@rice.edu>
Date: 7 Oct 90 21:30:00 GMT
Sender: sun-spots-request@rice.edu
Organization: Sun-Spots
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Approved: Sun-Spots@rice.edu
Originator: spots@walhalla.rice.edu
X-Sun-Spots-Digest: Volume 9, Issue 334, message 7

Sun fortran (1.3.1) allows me to write variable-length unformatted records
on tape.  It attaches the recordlength to the record itself by adding a
4-byte integer both before and after the record.  (It's put after the
record to allow backspacing).  What I can't understand is how to read the
records if I don't know how long they're going to be.  As far as I can
tell, if the list of variables in an unformatted read doesn't exactly
match the length of the tape record, it's an error.  If I was doing
formatted I/O the Q format would help.  There doesn't seem to be an
equivalent for unformatted operations.

Am I missing something?  Am I going to have to write subroutines in C to
call open(2) and read(2), and handle the recordlength bytes by hand?

* Patrick Nolan              *  Bitnet: PLN@SLACVM                   *
* Hansen Laboratories        *  Internet: nolan@meggie.stanford.edu  *