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From: ark@alice.UUCP (Andrew Koenig)
Newsgroups: comp.lang.c
Subject: Re: Why 'struct foo *x' instead of 'foo *x'
Message-ID: <9405@alice.UUCP>
Date: 29 May 89 03:32:17 GMT
References: <26575@watmath.waterloo.edu> <10213@claris.com> <878@m3.mfci.UUCP>
Organization: AT&T Bell Laboratories, Liberty Corner NJ
Lines: 39

In article <878@m3.mfci.UUCP>, karzes@mfci.UUCP (Tom Karzes) writes:
> In article <9137@csli.Stanford.EDU> jkl@csli.stanford.edu (John Kallen) writes:
> >
> >Does anybody know the reason why structs are defined as they are in C?
> >I.e. why do I have to say "struct foo" instead of just the tag "foo"?

> I think one reason is that it allows pointers to foo before foo itself is
> actually defined.  For example:

>     struct foo {
>         struct bar *pb;
>     };

>     struct bar {
>         struct foo *pf;
>     };

You can say `foo' instead of `struct foo' in C++.

It handles the forward reference problem in one of two ways.

One is to allow `struct foo' as a type name even if `foo' has
not yet been defined.  That makes the example above legal.

The other way is to allow the existence of a type name
to be established before the definition in some circumstances:

	struct bar;

	struct foo {
		bar *pb;
	};

	struct bar {
		foo *pf;
	};
-- 
				--Andrew Koenig
				  ark@europa.att.com