casting non const to const in c++

Question

I know that you can use const_cast to cast a const to a non-const.

But what should you use if you want to cast non-const to const?

Answer 1

const_cast can be used in order remove or add constness to an object. This can be useful when you want to call a specific overload.

Contrived example:

class foo {     int i; public:     foo(int i) : i(i) { }      int bar() const {         return i;         }      int bar() { // not const         i++;         return const_cast<const foo*>(this)->bar();      } }; 

Answer 2

STL since C++17 now provides std::as_const for exactly this case.

See: http://en.cppreference.com/w/cpp/utility/as_const

Use:

CallFunc( as_const(variable) ); 

Instead of:

CallFunc( const_cast<const decltype(variable)>(variable) );