Re: on understanding & and pointer arithmetic

From	Bart <bc@freeuk.com>
Newsgroups	comp.lang.c
Subject	Re: on understanding & and pointer arithmetic
Date	2021-12-16 14:23 +0000
Organization	A noiseless patient Spider
Message-ID	<spfi5g$6ko$1@dont-email.me> (permalink)
References	<86a6h0eiy9.fsf@levado.to>

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On 16/12/2021 14:13, Meredith Montgomery wrote:
> I'm investigating the syntax array[index] and I'm getting surprised at
> some places.  My intuition says that a[3] is the same as a + 3.

It's the same as *(a+3).

However if a is an array of arrays, then the array element at *(a+3) 
might decay to a pointer of that array, so it could end up as the same 
value as a+3, if different type:

     int a[5][4];

     printf("%p\n", a[3]);
     printf("%p\n", *(a+3));
     printf("%p\n", a+3);

These all show the same address. But change 'a' to 'int a[5]', and the 
first two lines show the value, the element a[3] (some random value if 
not initialised), and the last shows the address of that element.

> I also
> know that /&a/ is the same as /a/.

The same /what/? Those have the same values but different types ((T*)[] 
vs T* where T is a's element type).

Thread

on understanding & and pointer arithmetic Meredith Montgomery <mmontgomery@levado.to> - 2021-12-16 11:13 -0300
  Re: on understanding & and pointer arithmetic Bart <bc@freeuk.com> - 2021-12-16 14:23 +0000
    Re: on understanding & and pointer arithmetic Meredith Montgomery <mmontgomery@levado.to> - 2021-12-16 11:57 -0300
      Re: on understanding & and pointer arithmetic Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-12-16 17:42 +0000
        Re: on understanding & and pointer arithmetic Bart <bc@freeuk.com> - 2021-12-16 18:14 +0000
          Re: on understanding & and pointer arithmetic Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-12-16 21:14 +0000
        Re: on understanding & and pointer arithmetic Meredith Montgomery <mmontgomery@levado.to> - 2021-12-16 16:42 -0300
          Re: on understanding & and pointer arithmetic Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-12-16 12:44 -0800
            Re: on understanding & and pointer arithmetic Meredith Montgomery <mmontgomery@levado.to> - 2021-12-18 12:06 -0300
          Re: on understanding & and pointer arithmetic Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-12-16 21:34 +0000
            Re: on understanding & and pointer arithmetic Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-12-16 14:14 -0800
              Re: on understanding & and pointer arithmetic Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-12-16 23:44 +0000
            Re: on understanding & and pointer arithmetic Meredith Montgomery <mmontgomery@levado.to> - 2021-12-18 12:09 -0300
  Re: on understanding & and pointer arithmetic David Brown <david.brown@hesbynett.no> - 2021-12-16 16:23 +0100
    Re: on understanding & and pointer arithmetic Meredith Montgomery <mmontgomery@levado.to> - 2021-12-16 16:25 -0300
      Re: on understanding & and pointer arithmetic David Brown <david.brown@hesbynett.no> - 2021-12-16 21:08 +0100
        Re: on understanding & and pointer arithmetic Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-12-16 12:54 -0800
          Re: on understanding & and pointer arithmetic David Brown <david.brown@hesbynett.no> - 2021-12-17 10:53 +0100
            Re: on understanding & and pointer arithmetic Meredith Montgomery <mmontgomery@levado.to> - 2021-12-18 11:39 -0300
              Re: on understanding & and pointer arithmetic scott@slp53.sl.home (Scott Lurndal) - 2021-12-18 16:31 +0000
              Re: on understanding & and pointer arithmetic David Brown <david.brown@hesbynett.no> - 2021-12-18 18:56 +0100
                Re: on understanding & and pointer arithmetic Meredith Montgomery <mmontgomery@levado.to> - 2021-12-25 21:29 -0300
              Re: on understanding & and pointer arithmetic Bart <bc@freeuk.com> - 2021-12-18 18:29 +0000
        Re: on understanding & and pointer arithmetic Meredith Montgomery <mmontgomery@levado.to> - 2021-12-18 11:32 -0300
    Re: on understanding & and pointer arithmetic Manfred <noname@add.invalid> - 2021-12-16 21:34 +0100
      Re: on understanding & and pointer arithmetic Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-12-16 22:20 +0000
        Re: on understanding & and pointer arithmetic Meredith Montgomery <mmontgomery@levado.to> - 2021-12-18 12:02 -0300
          Re: on understanding & and pointer arithmetic Meredith Montgomery <mmontgomery@levado.to> - 2021-12-18 12:34 -0300
          Re: on understanding & and pointer arithmetic Manfred <noname@add.invalid> - 2021-12-18 18:36 +0100
          Re: on understanding & and pointer arithmetic Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-12-18 21:17 +0000
      Re: on understanding & and pointer arithmetic James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-12-16 18:59 -0500
  Re: on understanding & and pointer arithmetic James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-12-16 18:38 -0500
    Re: on understanding & and pointer arithmetic Bart <bc@freeuk.com> - 2021-12-16 23:50 +0000
      Re: on understanding & and pointer arithmetic "james...@alumni.caltech.edu" <jameskuyper@alumni.caltech.edu> - 2021-12-17 07:34 -0800
        Re: on understanding & and pointer arithmetic Bart <bc@freeuk.com> - 2021-12-17 17:48 +0000
    Re: on understanding & and pointer arithmetic Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-12-16 23:56 +0000
      Re: on understanding & and pointer arithmetic James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-12-16 19:06 -0500
        Re: on understanding & and pointer arithmetic Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-12-17 00:10 +0000
        Re: on understanding & and pointer arithmetic Meredith Montgomery <mmontgomery@levado.to> - 2021-12-18 12:32 -0300
    Re: on understanding & and pointer arithmetic Meredith Montgomery <mmontgomery@levado.to> - 2021-12-18 12:30 -0300
  Re: on understanding & and pointer arithmetic David Brown <david.brown@hesbynett.no> - 2021-12-17 11:08 +0100
    Re: on understanding & and pointer arithmetic Manfred <noname@add.invalid> - 2021-12-17 16:24 +0100
      Re: on understanding & and pointer arithmetic David Brown <david.brown@hesbynett.no> - 2021-12-17 18:17 +0100
    Re: on understanding & and pointer arithmetic Meredith Montgomery <mmontgomery@levado.to> - 2021-12-18 12:11 -0300

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