Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!watmath!clyde!burl!ulysses!allegra!princeton!caip!nike!ucbcad!ucbvax!sdcsvax!sdcrdcf!psivax!friesen
From: friesen@psivax.UUCP (Stanley Friesen)
Newsgroups: net.lang.c
Subject: Re: C'mon, guys!
Message-ID: <1263@psivax.UUCP>
Date: Fri, 13-Jun-86 15:06:07 EDT
Article-I.D.: psivax.1263
Posted: Fri Jun 13 15:06:07 1986
Date-Received: Tue, 17-Jun-86 20:21:11 EDT
References: <200@pyuxv.UUCP> <1181@ncoast.UUCP> <350@dg_rtp.UUCP>
Reply-To: friesen@psivax.UUCP (Stanley Friesen)
Organization: Pacesetter Systems Inc., Sylmar, CA
Lines: 53

In article <769@aimmi.UUCP> gilbert@aimmi.UUCP (Gilbert Cockton) writes:
>
>Despite reading three years of discussion on and off on the pointer-array
>equivalance topic, as a casual user of C, I've never been able to come
>up with a clear view on when pointers and arrays are equivalent.
>I'm sure much of my confusion has actually been caused by reading the
>news.
>
>Any volunteers for a simple set of statements that get the message
>across? There must be many C compiler experts out there.
>

	OK, I'll try. First statement

 * A two-dimensional array is an array of one-dimensional arrays, and
   multi-dimensioanl arrays are produced by repeating this composition
   process.

>All I can start with is a straw man, as I'm no expert. 
>
>* given an array of dimensions a x b x c .. x n,
>  the array name is a pointer to array[0][0][0]..[0]
>
      * Close, the array name is a *constant* pointer to the first
	b x c x .. x n dimensional *subarray*, i.e. to array[0].

>* the only time this is any real use if when passing arrays by reference
>  as `array' is easier and safer to write than
>
>	  &(array[0][0][0]..[0])
>
>  as you don't need to bear the array dimensions in mind.

      * I would say its real use is to allow writing algorithms which
	may be applied to any one of several similar arrays by using
	a pointer instead of an array and initializing the pointer to
	the first element of the array. (especially since 'array' is
	equivalent to '&(array[0])' rather than the longer form you
	suggest)


	To summarize, given the declaration:

TYPE array[a][b][c]...[n];

	the following two usages are equivalent:
	array		&array[0]
-- 

				Sarima (Stanley Friesen)

UUCP: {ttidca|ihnp4|sdcrdcf|quad1|nrcvax|bellcore|logico}!psivax!friesen
ARPA: ??