Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!cmcl2!adm!smoke!gwyn
From: gwyn@smoke.BRL.MIL (Doug Gwyn)
Newsgroups: comp.lang.c
Subject: Re: Help, page 197 K&R !!!
Keywords: structures.
Message-ID: <10480@smoke.BRL.MIL>
Date: 2 Jul 89 03:21:43 GMT
References: <646@kl-cs.UUCP>
Reply-To: gwyn@brl.arpa (Doug Gwyn)
Organization: Ballistic Research Lab (BRL), APG, MD.
Lines: 32

In article <646@kl-cs.UUCP> atula@cs.keele.ac.uk (Atula Herath) writes:
>"Two structures may share a common initial sequence of members; ..."
>What does that mean ?

This is explained in A8.3 in the second edition of K&R, which reflects
the current state of C structure member name constraints.  According
to K&R 1st ed., structure member names for all structure types together
constituted one big name space; however, that's not how C is currently
defined -- now each structure type has a private name space for its
members, so the same member name may be freely used in a variety of
declarations of different structures.  The cited quotation is simply
not relevant under the current member name space rules.

K&R 1st ed.:
	struct foo {
		int a;
		float b;
	};
	struct bar {
		int a;		/* legal */
		char c;
	};
	struct baz {
		double a;	/* illegal */
		int d;
	};
	struct bam {
		float e;
		int a;		/* illegal */
	};

All the above are legal according to modern rules.