Path: csiph.com!eternal-september.org!feeder.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail
From: Keith Thompson <kst-u@mib.org>
Newsgroups: comp.lang.c
Subject: Re: C declarations
Date: Mon, 30 Jan 2017 11:42:57 -0800
Organization: None to speak of
Lines: 27
Message-ID: <lnwpdc9vwe.fsf@kst-u.example.com>
References: <o6nd9u$rp1$1@dont-email.me> <o6nepi$1l5$1@dont-email.me>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Injection-Info: mx02.eternal-september.org; posting-host="a9fae22b5f567322e337da4e19df7ab9"; logging-data="25319"; mail-complaints-to="abuse@eternal-september.org";	posting-account="U2FsdGVkX1+rCtPb9tbLb7rmjUj39zk1"
User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.1 (gnu/linux)
Cancel-Lock: sha1:AQbKbeLBSydruGdCTCKm0TWwTS8= sha1:LgYJDLvyJlLwVFZDO0GNlkvo3YI=
Xref: csiph.com comp.lang.c:102787

David Brown <david.brown@hesbynett.no> writes:
> On 30/01/17 14:00, BartC wrote:
[...]
>> Then there is this, also outside a function, although more compilers
>> complain about it:
>> 
>>   *p = 10;
>> 
>> This presumably declares p to be of type int*, and initialises it to 10.
>
> Again, I believe it is legal syntax in C90.  It has undefined behaviour
> (due to the conversion from an integer).

I believe it's legal syntax, but it's a constraint violation.  There is
no implicit conversion from int to int* (other than the special case of
a null pointer constant).

Pre-ANSI C compilers commonly permitted implicit conversions between
pointers and integers, but C89/C90 did not.

[...]

-- 
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"