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Re: Description of "." operator

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Keith Thompson <kst-u@mib.org> writes:
> N1570 6.5.2.3p3 says:
>
>     A postfix expression followed by the . operator and an identifier
>     designates a member of a structure or union object. The value
>     is that of the named member, and is an lvalue if the first
>     expression is an lvalue.
>
> Consider the use of the word "object" in the first sentence.
>
> An expression of struct type doesn't necessarily refer to an *object* of
> that type.  For example:
>
>     struct pair { int x; int y; };
>     struct pair func(void) {
>         struct pair result = { 10, 20 };
>         return result;
>     }
>     ...
>     int y = func().y;
>
> And the second quoted sentence seems to explictly acknowledge that the
> left operand needn't refer to an object.
>
> Shouldn't the phrase "a member of a structure or union object" be "a
> member of a structure or union *value*"?

Or, perhaps better, "a member of a structure or union *expression*".

> If not, in the example code above, what object is being referred to?
> ("result" no longer exists after the function returns.)

-- 
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"

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Thread

Description of "." operator Keith Thompson <kst-u@mib.org> - 2012-12-07 18:34 -0800
  Re: Description of "." operator Keith Thompson <kst-u@mib.org> - 2012-12-08 10:43 -0800
    Re: Description of "." operator Jens Gustedt <jens.gustedt@loria.fr> - 2012-12-10 00:35 +0100
      Re: Description of "." operator Keith Thompson <kst-u@mib.org> - 2012-12-09 20:02 -0800
  Re: Description of "." operator jgk@panix.com (Joe keane) - 2012-12-09 23:34 +0000
    Re: Description of "." operator Keith Thompson <kst-u@mib.org> - 2012-12-09 20:00 -0800
  Re: Description of "." operator Tim Rentsch <txr@alumni.caltech.edu> - 2012-12-20 23:32 -0800
    Re: Description of "." operator Keith Thompson <kst-u@mib.org> - 2012-12-21 02:08 -0800
      Re: Description of "." operator Eric Sosman <esosman@comcast-dot-net.invalid> - 2012-12-21 09:18 -0500
        Re: Description of "." operator Tim Rentsch <txr@alumni.caltech.edu> - 2012-12-21 08:45 -0800
      Re: Description of "." operator Tim Rentsch <txr@alumni.caltech.edu> - 2012-12-21 08:37 -0800
  Re: Description of "." operator Shao Miller <sha0.miller@gmail.com> - 2013-01-06 01:23 -0500
    Re: Description of "." operator Keith Thompson <kst-u@mib.org> - 2013-01-05 23:51 -0800
      Re: Description of "." operator Shao Miller <sha0.miller@gmail.com> - 2013-01-06 13:49 -0500
        Re: Description of "." operator Keith Thompson <kst-u@mib.org> - 2013-01-06 22:12 -0800
          Re: Description of "." operator Shao Miller <sha0.miller@gmail.com> - 2013-01-17 23:19 -0500
            Re: Description of "." operator Shao Miller <sha0.miller@gmail.com> - 2013-01-18 20:47 -0500
              Re: Description of "." operator Keith Thompson <kst-u@mib.org> - 2013-01-18 20:14 -0800
              Re: Description of "." operator jgk@panix.com (Joe keane) - 2013-01-20 20:07 +0000
                Re: Description of "." operator Shao Miller <sha0.miller@gmail.com> - 2013-01-20 15:36 -0500

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