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From: Keith Thompson <kst-u@mib.org>
Newsgroups: comp.lang.c
Subject: Re: Difference between these pointer syntaxes
Date: Sat, 27 Aug 2016 12:07:10 -0700
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James Kuyper <jameskuyper@verizon.net> writes:
[...]
> C is built on the premise that only pointer values can be indexed or
> dereferenced, with pointer[index] being exactly equivalent to
> *(pointer+index), and that lvalues of array type automatically convert
> into pointer values, allowing that rule to apply to them. There's no
> internal inconsistency in that formulation, just an inconsistency
> between that approach and the one you insist on following.
[...]

I've seen some people attempt to simplify the rules for when array
expressions are "converted" to pointer expressions by saying that
array *lvalues* are converted to pointer values.  That's not
accurate.  For example, in `&array_object`, the subexpression
`array_object` is clearly an lvalue (the operand of unary `&` has to
be), but it's not converted.  (I'm not sure that's what you're trying
to do.  If not, I'm just hijacking your statement to make a point.)

In fact *all* expressions of array type are lvalues (I'm not quite
100% certain of that).  You need to enumerate the three exceptions
to determine when they are and are not converted to pointers.

(One corner case is an array member of a struct or union value
that is the result of a function call.  C11 added the concept of
"temporary lifetime" to account for this.)

-- 
Keith Thompson (The_Other_Keith) kst-u@mib.org  <http://www.ghoti.net/~kst>
Working, but not speaking, for JetHead Development, Inc.
"We must do something.  This is something.  Therefore, we must do this."
    -- Antony Jay and Jonathan Lynn, "Yes Minister"