C++ takes reference functionality one step higher by introducing reference wrappers!

A reference wrapper is a copy-constructible and copy-assignable wrapper for a object of type&, which is defined in the header <functional>. So you have an object, that behaves like a reference, but can be copied. Contrary to classic references, std::reference_wrapper objects support two additional use cases:

  • You can use them in containers of the Standard Template Library. std::vector<std::reference_wrapper<int>> myIntRefVector
  • You can copy instances of classes, which have std::reference_wrapper objects. That is in general not possible with references.

To access the reference of a std::reference_wrapper<int> myInt(1), the get method can be used: myInt.get(). You can use a reference wrapper to encapsulate and invoke a callable.

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