Re: MSDN const_cast sample

From:

=?Utf-8?B?R2Vvcmdl?= <George@discussions.microsoft.com>

Newsgroups:

microsoft.public.vc.language

Date:

Thu, 20 Dec 2007 06:18:00 -0800

Message-ID:

<697E3FFB-98B9-4FB8-9D0F-92020EA8D10F@microsoft.com>

Thanks igor,

About my confusion about sample, I think in the sample, there should be some
code to modify the value of a variable which is added const qualifier, but
actually not const from definition. But in the sample, I can not see such
code. Could you show me please?

void mutate(const int&);
void f(const int* const p)
{
int j = *p;
mutate(*p);
cout << *p << j << endl;
}

int g_theRealVariable = 5;
f(&g_theRealVariable);

void mutate(const int& i)
{
// modify i through a non-const alias
g_theRealVariable = 42;
}

regards,
George

"Igor Tandetnik" wrote:

"George" <George@discussions.microsoft.com> wrote in message
news:24241F1E-6887-4D79-A84D-26FED50EC856@microsoft.com

back even without const_cast, staying fully within C++ type system.
This means that the optimizer is not, after all, allowed to cache
the "const" value in this situation, which in turn means that
const_cast doesn't

How will compiler make use of the cached value in the future?

It won't. Which part of "is not allowed to cache" do you find unclear?

BTW: the following sample is not valid, since in the sample, no value
is changed through pointer p and function f, right?

Looks perfectly valid to me. I don't understand your concerns. Where
exactly do you believe the sample violates any rules of the language?
--
With best wishes,
Igor Tandetnik

With sufficient thrust, pigs fly just fine. However, this is not
necessarily a good idea. It is hard to be sure where they are going to
land, and it could be dangerous sitting under them as they fly
overhead. -- RFC 1925