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From: peter@sugar.UUCP
Newsgroups: comp.lang.c
Subject: Re: Unions that generate offsets (?)
Message-ID: <720@sugar.UUCP>
Date: Mon, 14-Sep-87 11:45:33 EDT
Article-I.D.: sugar.720
Posted: Mon Sep 14 11:45:33 1987
Date-Received: Sat, 19-Sep-87 07:25:33 EDT
References: <167@jc3b21.UUCP>
Organization: Sugar Land UNIX - Houston, TX
Lines: 22
Keywords: union structure offset
Summary: "The compiler" is probably not your compiler.

In article <167@jc3b21.UUCP>, crash@jc3b21.UUCP (Frank (Crash) Edwards) writes:
> 	"Actually, the compiler checks only that a name in two different
> 	structures has the same type and offset in both, but if preceding
> 	members differ the construction is non-portable."

> First of all, this paragraph should read, "but if preceding member *types*
> differ".  Since the compiler checks offsets, the construction is non-
> portable only if the offset might change during porting.

> Again the reference "the compiler" -- as if only *one* compiler existed!

The book was written when basically only one compiler existed. The compiler
described is the PDP-11 K&R compiler. Most modern 'C' compilers do check
on the types of the structure and the member and will complain. Thus the
construction is non-portable.

Whenever K&R talks about "the compiler", that should cue you to regard
the associated text as being suspect unless you're using a PDP-11 running
version 6 or version 7 UNIX.
-- 
-- Peter da Silva `-_-' ...!hoptoad!academ!uhnix1!sugar!peter
--                 'U`      ^^^^^^^^^^^^^^ Not seismo!soma (blush)