Re: const_cast<>

From: Jack Klein (jackklein_at_spamcop.net)
Date: 11/13/03 

Date: Thu, 13 Nov 2003 04:58:29 GMT

On Thu, 13 Nov 2003 10:06:02 +0530, "R. Anbeeswaran"
<Ramachandran.Anbeeswaran@sisl.co.in> wrote in comp.lang.c++:

> Hi All,
>
> void main()

There is no such thing as "void main()" in C++. The ANSI/ISO standard
requires "int main()" ALWAYS. In fact, a conforming C compiler is
required to issue a diagnostic message for "void main()".

> {
> const int i = 20;
> int *p = const_cast<int*>(&i);
>

Attempting to modify a variable that was defined as const produces
undefined behavior. The C++ standard no longer knows or cares what
your program does. Anything that happens is just as right or wrong as
anything else.

> cout <<"i="<< i <<"\t"<<"*p="<<*p<<"\n";
> }
>
> In the output of the prog. is :
>
> i=20 *p=40
>
> How is it true? (p is pointing to i). How is the particular address
> referenced to two different values?
> In the Quick Watch, (Visutal Studio is used for compilation & debug),
> the value of 'i' and '*p' are same. But, it is flashed out with the
> different values? The result is same in the release mode also.
>
> All assistance are appreciated.

There is no point in asking why a particular compiler produces any
particular results once you invoke undefined behavior. 

-- 
Jack Klein
Home: http://JK-Technology.Com
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