Re: How to read "The lvalue-to-rvalue, array-to-pointer, and function-to-pointer standard conversionsare not applied to the left expressions"?

From:
 James Kanze <james.kanze@gmail.com>
Newsgroups:
comp.lang.c++
Date:
Thu, 21 Jun 2007 08:46:12 -0700
Message-ID:
<1182440772.809324.253850@p77g2000hsh.googlegroups.com>
On Jun 21, 12:32 pm, Lighter <cqu...@gmail.com> wrote:

Thank you very much, James.

Please see an example:

int a[2];
int* p;
int* p2 = (p = a, p++); // Note here, p = a is a array-to-pointer
conversion.


OK. I understand where your problem is.

"p = a" is not an array-to-pointer conversion, because the type
of "p = a" is int*; the type of an assignment expression is
always the type of the lvalue being assigned.

There is an array-to-pointer conversion *in* the expression, but
the expression itself isn't subject to the conversion: if the
results of "p = a" were an array, no conversion would take
place. The expression "a" is not the expression to the right of
the comma operator; the expression "p = a" is. The expression
"a" is the expression to the left of an assignment operator,
where the rvalue to lvalue conversion takes place (which
automatically means that the array-to-pointer conversion is
active).

the code above can be compiled without any warning with VS 2005. Why?


Because it's legal.

What is the reason of the standard's making such a rule? That is what
I really want to see. Could give me an explaination?


See above. The text concerns only the operands of the comma
operator. The sub-expressions of that expression are not
concerned.

--
James Kanze (GABI Software, from CAI) email:james.kanze@gmail.com
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