Question about const_cast in c++

Question

all: this is quoted from Effective C++ 3rd editiion

const_cast is typically used to cast away the constness of objects. It is the only C++-style ca

Answer 1

You don't need const_cast to add constness:

class C;
C c;
C const& const_c = c;

The other way around needs a const_cast though

const C const_c;
C& c = const_cast(const_c);

but behavior is undefined if you try to use non-const operations on c.

By the way, if you don't use a reference, a copy of the object is to be made:

C d = const_c; // Copies const_c