Re: Different types of cast

From:

James Kanze <james.kanze@gmail.com>

Newsgroups:

comp.lang.c++

Date:

Fri, 25 Dec 2009 05:00:39 -0800 (PST)

Message-ID:

<986dced3-0116-47c1-86c0-1662ffdfa4f2@c34g2000yqn.googlegroups.com>

On Dec 24, 9:16 am, Ian Collins <ian-n...@hotmail.com> wrote:

Tomislav Novak wrote:

On 2009-12-24, Christof Warlich <cwarl...@gmx.de> wrote:

Ravi wrote:

What is the difference between static cast and reinterpret cast?

With static_cast you may only cast within the same inheritance
hierarchy, i.e. it is more restrictive and thus somewhat safer.

static_cast also enables one to convert between types with
implicit or explicit conversion operators.

dynamic_cast is similar, adding run-time checking and
making the cast really safe.

reinterpret_cast allows any cast.

Of course, it works for pointer types only (just to clarify further).

No, it works for any type with the same size.

Size has nothing to do with it. For a reinterpret_cast to be
legal, one of its operands must be a pointer or a reference.
A pointer can also be cast to and from an integral type (with
some restrictions concerning whether it fits in such cases).

But as I said in my reponse to the OP, the important difference
is semantics: a reinterpret_cast has distinctly different
semantics from a static_cast, even in the cases where both are
legal.

But it can't be used to cast away const or volatile.

That's true for all of the casts mentionned. (Note, however,
that since the result of a conversion is only an lvalue if the
conversion is to a reference, top level const or volatile is
irrelevant and ignored.)

--
James Kanze