C++ Memory Library const_pointer_cast

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Description

It returns a copy of sp of the proper type with its stored pointer const casted from U* to T*.

Declaration

Following is the declaration for std::const_pointer_cast.

template <class T, class U>
  shared_ptr<T> const_pointer_cast (const shared_ptr<U>& sp) noexcept;

C++11

template <class T, class U>
  shared_ptr<T> const_pointer_cast (const shared_ptr<U>& sp) noexcept;

Parameters

sp − Its a shared pointer.

Return Value

It returns a copy of sp of the proper type with its stored pointer const casted from U* to T*.

Exceptions

noexcep − It doesn't throw any exceptions.

Example

In below example explains about std::const_pointer_cast.

#include <iostream>
#include <memory>

int main () {
   std::shared_ptr<int> foo;
   std::shared_ptr<const int> bar;

   foo = std::make_shared<int>(100);

   bar = std::const_pointer_cast<const int>(foo);

   std::cout << "*bar: " << *bar << '\n';
   *foo = 200;
   std::cout << "*bar: " << *bar << '\n';

   return 0;
}

Let us compile and run the above program, this will produce the following result −

*bar: 100
*bar: 200