Re: static_cast vs reinterpert_cast
Hi,
static_cast is meant to be used for cases which the compiler would
automatically be able to convert, such as char to int and in your case
A* to void*. reinterpret_cast is used, as the book mentions, for
low-level hacks, especially when you know what you are doing, eg:
struct S
{
int a, b;
};
int main()
{
S s;
s.a = 10;
s.b = 20;
int* p = reinterpret_cast<int*>(&s);
cout << "a=" << *p << endl;
++p;
cout << "b=" << *p << endl;
}
Typically reinterpret_cast should work where a static_cast works.
"Ideally" in C++ we should avoid using void* as much because we loose
type safety. Also in your case you do seem to be having a class
hierarchy (A,B), so using virtual functions with base ptrs would be
cleaner (if virtual fn overhead is not an issue).
Thanks and regards
Sonison James
Rahul wrote:
Hi,
I have a
class A : public B {...member functions......data members};
and am doing the following
A *p=new A();
void *p=static_cast<void *>(p);
factory_instance->process(p);
Here p is passed to a function, which accepts void ptr. That function
need to cast it back
A *pp=static_cast<A *>(p);
The function is in the factory which accepts void *p only, the specific
implementations need to cast the pointer back to the expected class
and use it.
Question:Though both works fine, yet I want to know what is more
appropriate in this situation static_cast OR reinterpert_cast
The books suggests
static_cast=> "For "well-behaved" and "reasonably
well-behaved" casts,including things you might now do without a cast
reinterpret_cast=> To cast to a completely different meaning. The key
is that you'll need to cast back to the original type to use it
safely.
But I am not able to interpret the sentences in this context :-)