Path: utzoo!attcan!uunet!tut.cis.ohio-state.edu!purdue!haven!mimsy!chris
From: chris@mimsy.umd.edu (Chris Torek)
Newsgroups: comp.lang.c
Subject: Re: How to include char arrays of pointers in structures
Message-ID: <24109@mimsy.umd.edu>
Date: 2 May 90 07:30:32 GMT
References: <374@comcon.UUCP> <23890@mimsy.umd.edu> <23760@unix.cis.pitt.edu> <24003@mimsy.umd.edu>
Organization: U of Maryland, Dept. of Computer Science, Coll. Pk., MD 20742
Lines: 37

In article <24003@mimsy.umd.edu> I wrote:
>(You should get a diagnostic for this ... because the type of &a is
>(char *(*)[10]), while the type of ptr is (char *(*)[]), and the numbers
>in the brackets do not match.)

Norman Diamond has pointed out that the ANSI C standard says otherwise:
a pointer to an incomplete array type (one without a size) is compatible
with a pointer to a complete array type of any size, provided that
the types match when the size is not considered.  In other words,
a pointer of type

	T (*)[]

is compatible with both one of type

	T (*)[10]

and

	T (*)[20] ,

and a pointer of type

	T (*)[3]

is compatible with one of type

	T (*)[] .

This does not, however, affect my original point: there is nothing you
can do with a pointer of type (T (*)[]) that you cannot do with one of
type (T *), except confuse a human reading your code.  (There *is*
something new you can do if you put a number inside the brackets.  This
rule should be applied only to pointers to `sizeless' arrays.)
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7163)
Domain:	chris@cs.umd.edu	Path:	uunet!mimsy!chris