Path: ...!weretis.net!feeder8.news.weretis.net!fu-berlin.de!uni-berlin.de!not-for-mail
From: ram@zedat.fu-berlin.de (Stefan Ram)
Newsgroups: comp.lang.c
Subject: "array"
Date: 2 Apr 2025 11:01:01 GMT
Organization: Stefan Ram
Lines: 59
Expires: 1 Mar 2026 11:59:58 GMT
Message-ID: <array-20250402114422@ram.dialup.fu-berlin.de>
Mime-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
X-Trace: news.uni-berlin.de jGMNT7AqJkGADxOb73ZU3wkV/2s7+/L2yTbi39VhG00hJU
Cancel-Lock: sha1:MX40azWVLMfn0vjipLg1VFzwNno= sha256:09BGYdMg42hhHkaJxlFjnyDSjKS4u7RO8ryF1/MZehU=
X-Copyright: (C) Copyright 2025 Stefan Ram. All rights reserved.
	Distribution through any means other than regular usenet
	channels is forbidden. It is forbidden to publish this
	article in the Web, to change URIs of this article into links,
        and to transfer the body without this notice, but quotations
        of parts in other Usenet posts are allowed.
X-No-Archive: Yes
Archive: no
X-No-Archive-Readme: "X-No-Archive" is set, because this prevents some
	services to mirror the article in the web. But the article may
	be kept on a Usenet archive server with only NNTP access.
X-No-Html: yes
Content-Language: en-US
Bytes: 3157

  Below, an array is allocated dynamically.

#include <stdio.h>
#include <stdlib.h>

int main( void )
{ char *array_pointer = malloc( 10 * sizeof *array_pointer );
  if( !array_pointer )return EXIT_FAILURE;
  *array_pointer = 'a';
  free( array_pointer ); }

  But is it really an array according to the C spec?

  C only defines "array type", not array, but it uses ISO/IEC 2382:2015
  as a normative reference, and ISO/IEC 2382:2015 says:

|array
|An aggregate that is an instance of an array type and each
|element or appropriate group of elements in which may be
|referenced randomly and independently of the others.
ISO/IEC 2382-15 (1998), 15.03.08 (Can't access newer versions!)

  . That block of memory that malloc allocated, does it have an
  array type? I'm not sure. So are we allowed to call it an array?
  I think the C community /would/ mostyly call this an array.

  Here's an attempt to give it an explicit array type:

#include <stdio.h>
#include <stdlib.h>

int main( void )
{ char( *array_pointer )[ 10 ]= malloc( sizeof *array_pointer );
  if( !array_pointer )return EXIT_FAILURE;
  ( *array_pointer )[ 0 ]= 'a';
  free( array_pointer ); }

  Is it now more of an array than before?

  In n3467:

|The effective type of an object that is not a byte array, for
|an access to its stored value, is the declared type of the
|object. 83)
from 6.5p6

|83) Allocated objects have no declared type.
footnote for 6.5p6

|For all other accesses to a byte array, the effective type of
|the object is simply the type of the lvalue used for the access.
from 6.5p6

  In my example programs, the lvalue for the access has the
  type "int". So, I can see that there's an int object, and
  - in a similar way - that there are other int objects behind it,
  but not necessarily that they form an array.