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From: peter@sugar.UUCP (Peter da Silva)
Newsgroups: comp.lang.c
Subject: Re: System V manuals (was Re: What real non-UNIX 'C' compilers...)
Message-ID: <830@sugar.UUCP>
Date: Sun, 27-Sep-87 21:53:36 EDT
Article-I.D.: sugar.830
Posted: Sun Sep 27 21:53:36 1987
Date-Received: Thu, 1-Oct-87 05:13:33 EDT
References: <672@sugar.UUCP> <3545@venera.isi.edu> <721@sugar.UUCP> <29156@sun.uucp>
Organization: Sugar Land UNIX - Houston, TX
Lines: 40

First of all, the generic System 5 release 2 manual are arranged the same way
as the SVID. I haven't seen the release 3 manuals. For that matter I haven't
seen release 3. I kind of wish I'd never seen release 2.

> The difference is not "'fread' is a library routine" (in fact,
> they're *both* library routines on most implementations, one just happens
> to be relatively trivial - at least on UNIX systems),

Yeh, but we're talking about UNIX systems here. What else would we be doing
with a UNIX manual? Read is the UNIX primitive for reading data from a file,
and as such it's intrinsically different from fread, which involves a fair
amount of code (stdio) that you may want to avoid dragging in (say, because
you're running out of space on a PDP-11 or IBM-PC). Other differences between
read and fread (and write and fwrite) include:

	[ I'm sure you're alreday familiar with most of these, but... ]

	read leaves the I/O pointer pointing at the next byte to read. This
is important because of the way UNIX deals with inhertance of file descriptors.
Consider the version 6 implementation of "if".

	writes to a pipe are atomic. fwrites probably aren't.

	a 1-byte read from a character special device in raw mode will
be satisfied by 1 byte. A 1-byte fread may not be.

	a 1-byte read from a pipe will be satisfied by 1 byte. A one byte
fread almost certainly won't be.

	consider the behaviour of fflush.

	consider what happens if a program traps out with data still in the
buffer.

	the syntax of fread is different from read (and I consider this a design
flaw of the same magnitude as giving bitwise-and its weird priority in 'C'.
-- 
-- Peter da Silva `-_-' ...!hoptoad!academ!uhnix1!sugar!peter
--                 'U`  Have you hugged your wolf today?
-- Disclaimer: These aren't mere opinions... these are *values*.