Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.std.c > #1741

Re: Second draft, "Safe arrays and pointers for C"

Show key headers only | View raw

Shao Miller <sha0.miller@gmail.com> writes:
> On August 30th, 2012, at 12:23:29, John Nagle published:
>> Safe arrays and pointers for C through compatible additions to the language
>
> Some feed-back, if you care:
>
> I don't really care for importing references from C++11.  C has long 
> passed by value (with the exception of arrays [which itself has an 
> exception in C89/C90]).

Strictly speaking, arrays are not an exception to the C rule that
function arguments are passed by value.  Given

    int arr[N];
    func(arr);

an array is not being passed as an argument; rather, a pointer is
being passed (by value, of course).  The implicit conversion of
the array expression to a pointer is unrelated to the fact that
it appears in a function call; the same conversion happens in
most contexts.

[...]

If C were to add some kind of pass-by-reference mechanism (other than
the existing pass-a-pointer-by-value), it might be useful to require
some distinguishing syntax on the call.  For example, assuming the
addition of a "ref" keyword:

    void increment(ref int n) {
        n ++;
    }

    int x = 42;
    /* increment(x); would be illegal */
    increment(ref x);
    /* now x == 43 */

-- 
Keith Thompson (The_Other_Keith) kst-u@mib.org  <http://www.ghoti.net/~kst>
    Will write code for food.
"We must do something.  This is something.  Therefore, we must do this."
    -- Antony Jay and Jonathan Lynn, "Yes Minister"

Back to comp.std.c | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

Second draft, "Safe arrays and pointers for C" John Nagle <nagle@animats.com> - 2012-08-30 12:48 -0700
  Re: Second draft, "Safe arrays and pointers for C" pacman@kosh.dhis.org (Alan Curry) - 2012-08-31 22:17 +0000
    Re: Second draft, "Safe arrays and pointers for C" John Nagle <nagle@animats.com> - 2012-08-31 17:26 -0700
      Re: Second draft, "Safe arrays and pointers for C" Hans-Bernhard Bröker <HBBroeker@t-online.de> - 2012-09-02 22:20 +0200
        Re: Second draft, "Safe arrays and pointers for C" BGB <cr88192@hotmail.com> - 2012-09-03 10:55 -0500
          Re: Second draft, "Safe arrays and pointers for C" Ike Naar <ike@iceland.freeshell.org> - 2012-09-03 16:39 +0000
            Re: Second draft, "Safe arrays and pointers for C" BGB <cr88192@hotmail.com> - 2012-09-03 13:18 -0500
  Re: Second draft, "Safe arrays and pointers for C" Jens Gustedt <jens.gustedt@loria.fr> - 2012-09-02 10:52 +0200
  Re: Second draft, "Safe arrays and pointers for C" Per <per.mathisen@gmail.com> - 2012-09-28 06:49 -0700
    Re: Second draft, "Safe arrays and pointers for C" John Nagle <nagle@animats.com> - 2012-09-28 11:36 -0700
      Re: Second draft, "Safe arrays and pointers for C" Per <per.mathisen@gmail.com> - 2012-10-01 09:38 -0700
        Re: Second draft, "Safe arrays and pointers for C" John Nagle <nagle@animats.com> - 2012-10-01 11:38 -0700
      Re: Second draft, "Safe arrays and pointers for C" Shao Miller <sha0.miller@gmail.com> - 2012-12-17 09:11 -0500
        Re: Second draft, "Safe arrays and pointers for C" Keith Thompson <kst-u@mib.org> - 2012-12-17 10:18 -0800
          Re: Second draft, "Safe arrays and pointers for C" Shao Miller <sha0.miller@gmail.com> - 2012-12-17 18:24 -0500
            Re: Second draft, "Safe arrays and pointers for C" Shao Miller <sha0.miller@gmail.com> - 2012-12-17 18:32 -0500
            Re: Second draft, "Safe arrays and pointers for C" Keith Thompson <kst-u@mib.org> - 2012-12-17 15:44 -0800

csiph-web