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From: jsdy@hadron.UUCP (Joseph S. D. Yao)
Newsgroups: net.lang.c
Subject: Re: A last word on arrays? Hah!
Message-ID: <389@hadron.UUCP>
Date: Sat, 3-May-86 10:44:46 EDT
Article-I.D.: hadron.389
Posted: Sat May  3 10:44:46 1986
Date-Received: Tue, 6-May-86 06:05:42 EDT
References: <4992@think.ARPA> <310@dg_rtp.UUCP>
Reply-To: jsdy@hadron.UUCP (Joseph S. D. Yao)
Organization: Hadron, Inc., Fairfax, VA
Lines: 30
Keywords: array, reference, parameter, struct
Summary: Nitpicking?  Maybe, but let's be clear.  (Array as arg)

In article <310@dg_rtp.UUCP> throopw@dg_rtp.UUCP (Wayne Throop) writes:
	[attribution removed]
>I do have comment on John Rose's proposals.  ...
>>         (3) Interpret current C practice of converting array arguments
>>             to pointers as passing them by reference; make sizeof()
>>             work consistently.
>
>Well.  Sizeof is indeed peculiar.  For example,
>sizeof(formal_array_name) yeilds your machine's pointer size.

Ouch.  First off (see that nit?), it took me two (admittedly
fraction-of-a-second) passes to understand that you were talking
about what sizeof yields [sp!] on an array declared as a formal
a r g u m e n t .  I spent at least half a sec wondering how you
dressed your arrays to go formal!  Second, though (if it's a nit,
it's a MONSTER!), the reason it yields one of the pointer sizes
of your machine is that there is no such thing, really, as an
array argument.  It's fairly clear that when you declare a formal
argument to a function, the C compiler coerces it from array-of-X
to pointer-to-X.  You are therefore taking the size of a pointer,
and it returns the size of that pointer (which size may depend on
the type of the thing to which you are pointing).

As usual, this has been discussed to death in earlier articles.
If someone has a copy of my long-ish tutorial on this subject,
please send it to me.  I promise not to re-post it more often than
every year or two, and flag it so you can junk it.
-- 

	Joe Yao		hadron!jsdy@seismo.{CSS.GOV,ARPA,UUCP}